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For other uses, see Asphalt (disambiguation). Note: The terms bitumen and asphalt are mostly interchangeable, Asphalt Repair Contractors in Woodmead  except where asphalt is used as a shorthand for asphalt concrete. Natural bitumen from the Dead Sea Refined asphalt The University of Queensland pitch drop experiment, demonstrating the viscosity of asphalt

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Asphalt (/ˈæsˌfɔːlt, -ˌfɑːlt/), also known as bitumen (UK English: /ˈbɪtʃəmən, ˈbɪtjʊmən/,[1] US English: /bɪˈt(j)uːmən, baɪˈt(j)uːmən/)[2] is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used.

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The primary use (70%) of asphalt Asphalt Driveway Paving Near Me is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.

The terms “asphalt” and “bitumen” are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, “asphalt” (or “asphalt cement”) is commonly used for a refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called “bitumen”, and geologists worldwide often prefer the term for the naturally occurring variety. Common colloquial usage often refers to various forms of asphalt as “tar”, as in the name of the La Brea Tar Pits.

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Naturally occurring asphalt is sometimes specified by the term “crude bitumen”. Asphalt Repair Contractors Its viscosity is similar to that of cold molasses[6][7] while the material obtained from the fractional distillation of crude oil boiling at 525 °C (977 °F) is sometimes referred to as “refined bitumen”. The Canadian province of Alberta has most of the world’s reserves of natural asphalt in the Athabasca oil sands, which cover 142,000 square kilometres (55,000 sq mi), an area larger than England.

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The word “asphalt” is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word meaning “asphalt/bitumen/pitch” which perhaps derives from ἀ-, “without” and σφάλλω (sfallō), “make fall”.  Asphalt Companies Hiring Near Me the first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall.[11] From the Greek, the word passed into late Latin, and thence into French (asphalte) and English (“asphaltum” and “asphalt”). In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the “asphaltic concrete” used to pave roads.

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The expression “bitumen” originated in the Sanskrit words jatu, meaning “pitch”, and jatu-krit, meaning “pitch creating” or “pitch producing” (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally gwitu-men (pertaining to pitch), and by others, pixtumens (exuding or bubbling pitch), which was subsequently shortened to bitumen, thence passing via French into English. From the same root is derived the Anglo-Saxon word cwidu (mastix), the German word Kitt (cement or mastic) and the old Norse word kvada.

In British English, “bitumen” is used instead of “asphalt”. The word “asphalt” is instead used to refer to asphalt concrete, a mixture of construction aggregate and asphalt itself (also called “tarmac” in common parlance). Bitumen mixed with clay was usually called “asphaltum”,[13] but the term is less commonly used today.[citation needed]

Brick

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In Australian English, “bitumen” is often used as the generic term for road surfaces.

In American English, “asphalt” is equivalent to the British “bitumen”. However, “asphalt” is also commonly used as a shortened form of “asphalt concrete” (therefore equivalent to the British “asphalt” or “tarmac”).

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In Canadian English, the word “bitumen” is used to refer to the vast Canadian deposits of extremely heavy crude oil,[14] while “asphalt” is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as “dilbit” in the Canadian petroleum industry, while bitumen “upgraded” to synthetic crude oil is known as “syncrude”, and syncrude blended with bitumen is called “synbit”.[15]

“Bitumen” is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. “Bituminous rock” is a form of sandstone impregnated with bitumen. The tar sands of Alberta, Canada are a similar material.

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Neither of the terms “asphalt” or “bitumen” should be confused with tar or coal tars.[further explanation needed]

See also: Asphaltene

The components of asphalt include four main classes of compounds:

The naphthene aromatics and polar aromatics are typically the majority components. Most natural bitumens also contain organosulfur compounds, resulting in an overall sulfur content of up to 4%. Nickel and vanadium are found at <10 parts per million, as is typical of some petroleum.

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The substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase.[16] “It is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large”.

Asphalt may be confused with coal tar, which is a visually similar black, thermoplastic material produced by the destructive distillation of coal. During the early and mid-20th century, when town gas was produced, coal tar was a readily available byproduct and extensively used as the binder for road aggregates. The addition of coal tar to macadam roads led to the word “tarmac”, which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, asphalt has completely overtaken the use of coal tar in these applications. Other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. “Pitch” is another term sometimes informally used at times to refer to asphalt, as in Pitch Lake.

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Bituminous outcrop of the Puy de la Poix, Clermont-Ferrand, France

The majority of asphalt used commercially is obtained from petroleum.[18] Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.

Natural deposits of bitumen include lakes such as the Pitch Lake in Trinidad and Tobago and Lake Bermudez in Venezuela. Natural seeps occur in the La Brea Tar Pits and in the Dead Sea.

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Bitumen also occurs in unconsolidated sandstones known as “oil sands” in Alberta, Canada, and the similar “tar sands” in Utah, US. The Canadian province of Alberta has most of the world’s reserves, in three huge deposits covering 142,000 square kilometres (55,000 sq mi), an area larger than England or New York state. These bituminous sands contain 166 billion barrels (26.4×10^9 m3) of commercially established oil reserves, giving Canada the third largest oil reserves in the world. Although historically it was used without refining to pave roads, nearly all of the output is now used as raw material for oil refineries in Canada and the United States.

Alley

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The world’s largest deposit of natural bitumen, known as the Athabasca oil sands, is located in the McMurray Formation of Northern Alberta. This formation is from the early Cretaceous, and is composed of numerous lenses of oil-bearing sand with up to 20% oil.[19] Isotopic studies show the oil deposits to be about 110 million years old.[20] Two smaller but still very large formations occur in the Peace River oil sands and the Cold Lake oil sands, to the west and southeast of the Athabasca oil sands, respectively. Of the Alberta deposits, only parts of the Athabasca oil sands are shallow enough to be suitable for surface mining. The other 80% has to be produced by oil wells using enhanced oil recovery techniques like steam-assisted gravity drainage.

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Much smaller heavy oil or bitumen deposits also occur in the Uinta Basin in Utah, US. The Tar Sand Triangle deposit, for example, is roughly 6% bitumen.

Bitumen may occur in hydrothermal veins. An example of this is within the Uinta Basin of Utah, in the US, where there is a swarm of laterally and vertically extensive veins composed of a solid hydrocarbon termed Gilsonite. These veins formed by the polymerization and solidification of hydrocarbons that were mobilized from the deeper oil shales of the Green River Formation during burial and diagenesis.

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Bitumen is similar to the organic matter in carbonaceous meteorites.[23] However, detailed studies have shown these materials to be distinct.[24] The vast Alberta bitumen resources are considered to have started out as living material from marine plants and animals, mainly algae, that died millions of years ago when an ancient ocean covered Alberta. They were covered by mud, buried deeply over time, and gently cooked into oil by geothermal heat at a temperature of 50 to 150 °C (120 to 300 °F). Due to pressure from the rising of the Rocky Mountains in southwestern Alberta, 80 to 55 million years ago, the oil was driven northeast hundreds of kilometres and trapped into underground sand deposits left behind by ancient river beds and ocean beaches, thus forming the oil sands.

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The use of natural bitumen for waterproofing, and as an adhesive dates at least to the fifth millennium BC, with a crop storage basket discovered in Mehrgarh, of the Indus Valley Civilization, lined with it.[25] By the 3rd millennia BC refined rock asphalt was in use, in the region, and was used to waterproof the Great Bath, Mohenjo-daro.

In the ancient Middle East, the Sumerians used natural bitumen deposits for mortar between bricks and stones, to cement parts of carvings, such as eyes, into place, for ship caulking, and for waterproofing.[3] The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon.

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The 1 kilometre (0.62 mi) long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis (ca. 800 BC) was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent.

Bitumen was used by ancient Egyptians to embalm mummies.[3][28] The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians’ primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake).

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Approximately 40 AD, Dioscorides described the Dead Sea material as Judaicum bitumen, and noted other places in the region where it could be found.[29] The Sidon bitumen is thought to refer to material found at Hasbeya.[30] Pliny refers also to bitumen being found in Epirus. It was a valuable strategic resource, the object of the first known battle for a hydrocarbon deposit—between the Seleucids and the Nabateans in 312 BC.

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In the ancient Far East, natural bitumen was slowly boiled to get rid of the higher fractions, leaving a thermoplastic material of higher molecular weight that when layered on objects became quite hard upon cooling. This was used to cover objects that needed waterproofing,[3] such as scabbards and other items. Statuettes of household deities were also cast with this type of material in Japan, and probably also in China.

In North America, archaeological recovery has indicated bitumen was sometimes used to adhere stone projectile points to wooden shafts.[32] In Canada, aboriginal people used bitumen seeping out of the banks of the Athabasca and other rivers to waterproof birch bark canoes, and also heated it in smudge pots to ward off mosquitoes in the summer.

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In 1553, Pierre Belon described in his work Observations that pissasphalto, a mixture of pitch and bitumen, was used in the Republic of Ragusa (now Dubrovnik, Croatia) for tarring of ships.

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An 1838 edition of Mechanics Magazine cites an early use of asphalt in France. A pamphlet dated 1621, by “a certain Monsieur d’Eyrinys, states that he had discovered the existence (of asphaltum) in large quantities in the vicinity of Neufchatel”, and that he proposed to use it in a variety of ways – “principally in the construction of air-proof granaries, and in protecting, by means of the arches, the water-courses in the city of Paris from the intrusion of dirt and filth”, which at that time made the water unusable. “He expatiates also on the excellence of this material for forming level and durable terraces” in palaces, “the notion of forming such terraces in the streets not one likely to cross the brain of a Parisian of that generation”.

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But the substance was generally neglected in France until the revolution of 1830. In the 1830s there was a surge of interest, and asphalt became widely used “for pavements, flat roofs, and the lining of cisterns, and in England, some use of it had been made of it for similar purposes”. Its rise in Europe was “a sudden phenomenon”, after natural deposits were found “in France at Osbann (Bas-Rhin), the Parc (Ain) and the Puy-de-la-Poix (Puy-de-Dôme)”, although it could also be made artificially.[35] One of the earliest uses in France was the laying of about 24,000 square yards of Seyssel asphalt at the Place de la Concorde in 1835.

Among the earlier uses of bitumen in the United Kingdom was for etching. William Salmon’s Polygraphice (1673) provides a recipe for varnish used in etching, consisting of three ounces of virgin wax, two ounces of mastic, and one ounce of asphaltum.[37] By the fifth edition in 1685, he had included more asphaltum recipes from other sources.

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The first British patent for the use of asphalt was “Cassell’s patent asphalte or bitumen” in 1834.[35] Then on 25 November 1837, Richard Tappin Claridge patented the use of Seyssel asphalt (patent #7849), for use in asphalte pavement,[39][40] having seen it employed in France and Belgium when visiting with Frederick Walter Simms, who worked with him on the introduction of asphalt to Britain.[41][42] Dr T. Lamb Phipson writes that his father, Samuel Ryland Phipson, a friend of Claridge, was also “instrumental in introducing the asphalte pavement (in 1836)”.[43] Indeed, mastic pavements had been previously employed at Vauxhall by a competitor of Claridge, but without success.

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Claridge obtained a patent in Scotland on 27 March 1838, and obtained a patent in Ireland on 23 April 1838. In 1851, extensions for the 1837 patent and for both 1838 patents were sought by the trustees of a company previously formed by Claridge. Claridge’s Patent Asphalte Company—formed in 1838 for the purpose of introducing to Britain “Asphalte in its natural state from the mine at Pyrimont Seysell in France”,—”laid one of the first asphalt pavements in Whitehall”.  Trials were made of the pavement in 1838 on the footway in Whitehall, the stable at Knightsbridge Barracks,”and subsequently on the space at the bottom of the steps leading from Waterloo Place to St. James Park”. “The formation in 1838 of Claridge’s Patent Asphalte Company (with a distinguished list of aristocratic patrons, and Marc and Isambard Brunel as, respectively, a trustee and consulting engineer), gave an enormous impetus to the development of a British asphalt industry”.[45] “By the end of 1838, at least two other companies, Robinson’s and the Bastenne company, were in production”,[50] with asphalt being laid as paving at Brighton, Herne Bay, Canterbury, Kensington, the Strand, and a large floor area in Bunhill-row, while meantime Claridge’s Whitehall paving “continue(d) in good order”.

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Asphalt Surfacing Company Cost Estimate Thru lanes indicated by arrows on California CR G4 (Montague Expressway) in Silicon Valley.

In the context of traffic control, a lane is part of a roadway (carriageway) that is designated for use by a single line of vehicles, to control and guide drivers and reduce traffic conflicts.[1] Most public roads (highways) have at least two lanes, one for traffic in each direction, separated by lane markings. On multilane roadways and busier two-lane roads, lanes are designated with road surface markings. Major highways often have two multi-lane roadways separated by a median.

Some roads and bridges that carry very low volumes of traffic are less than 15 feet (4.6 m) wide, and are only a single lane wide. Vehicles travelling in opposite directions must slow or stop to pass each other. In rural areas, these are often called country lanes. In urban areas, alleys are often only one lane wide. Urban and suburban one lane roads are often designated for one-way traffic.

Lane capacity varies widely due to conditions such as neighboring lanes, lane width, elements next to the road, number of driveways, presence of parking, speed limits, number of heavy vehicles and so on – the range can be as low as 1000 passenger cars / hour to as high as 4800 passenger cars /hour but mostly falls between 1500 and 2400 passenger cars / hour.[2]

The Ontario Highway 401 in the Greater Toronto area, with 17 travel lanes in 6 separate carriageways visible in the midground. Turning lane on the Rodovia BR-101 (Brazil) Play media Changing lanes, Gothenburg, Sweden Transfer lanes, connecting surface collector lanes with through lanes between two tunnels A left-turn merging lane in Germany, needing explanation by a crafted sign These usages lead to the phrases life in the slow lane and life in the fast lane, used to describe relaxed or busy lifestyles, respectively and used as the titles of various books and songs.

While in general, wider lanes are associated with a reduction in crashes,[7] in urban settings both narrow (less than 2.8 m) and wide (over 3.1~3.2 m) lanes increase crash risks.[8] Wider lanes (over 3.3~3.4m) are associated with 33% higher impact speeds, as well as higher crash rates. Carrying capacity is also maximal at a width of 3 to 3.1 metres (9.8 to 10.2 ft), both for motor traffic and for bicycles. Pedestrian volume declines as lanes widen, and intersections with narrower lanes provide the highest capacity for bicycles.[9] As lane width decreases, traffic speed diminishes.[10]

Advocates for safety of people walking and people on bikes, and many new urbanists disagree with traditional thinking in traffic engineering, saying that safety and capacity are not adversely impacted by reducing lanes widths to as little as 10 feet (3.0 m).[11] Moreover, wider travel lanes also increase exposure and crossing distance for pedestrians at intersections and midblock crossings.

assumed widths and heights in road design for Europe (in meters)

The widths of vehicle lanes typically vary from 9 to 15 feet (2.7 to 4.6 m). Lane widths are commonly narrower on low volume roads and wider on higher volume roads. The lane width depends on the assumed maximum vehicle width with an additional space to allow for lateral motion of the vehicle.

The maximum truck width had been 96 inches (2.438 m) in the Code of Federal Regulations of 1956 which matches with the width of eight-foot for shipping containers. This had been increased to 102 inches (2.591 m) in 1976 which explicitly states to be read as the slightly larger metric 2.6 metres (102.36 in) width respecting international harmonization.[12] The same applies to standards in Europe which had increased the allowable size of road vehicles with a current maximum of 2.55 metres (100.39 in) for most trucks and allowing 2.6 metres (102.36 in) for refrigerator trucks. The minimum extra space had been 0.20 metres (7.87 in) and it is currently assumed to be at least 0.25 metres (9.84 in) on each side. For roads with a lower amount of traffic it is allowed to build the second or third lane in the same direction to an assumed lower width for cars like 1.75 metres (68.90 in), however this is not recommended as a design principle for new roads as changes in the amount of traffic could make for unnecessarily increased risks in the future.

The Interstate Highway standards for the U.S. Interstate Highway System uses a 12-foot (3.7 m) standard for lane width, while narrower lanes are used on lower classification roads. In Europe, as laws and road width vary by country, the minimum widths of lanes is generally between 2.5 to 3.25 metres (8.2 to 10.7 ft).[13] The federal Bundesstraße interurban network in Germany defines a minimum of 3.5 metres (11 ft 6 in) for each lane for the smallest two lane roads with an additional 0.25 metres (9.84 in) on the outer sides and shoulders being at least 1.5 metres (59.06 in) on each side. A modern Autobahn divided highway will have two lanes per direction which are 3.75 metres (12 ft 4 in) wide with an additional clearance of 0.50 metres (19.69 in) on each side, while three lanes per direction are set at 3.75 metres (12 ft 4 in) for the rightmost lane and 3.5 metres (11 ft 6 in) for the other lanes. Urban access roads and roads in low-density areas may have lanes as small as 2.75 metres (9 ft 0 in) in width per lane with shoulders being at least 1 metre (3 ft 3 in) wide.[14]

Main article: Road surface marking A typical rural American freeway (Interstate 5 in the Central Valley of California). Notice the yellow line on the left, the dashed white line in the middle, and the solid white line on the right. Also note the rumble strip to the left of the yellow line.

Painted lane markings vary widely from country to country. In the United States, Canada, Mexico, Honduras, Puerto Rico, Virgin Islands and Norway, yellow lines separate traffic going opposite directions and white separates lanes of traffic traveling the same direction, but such is not the case in many European countries.

Lane markings are mostly lines painted on the road by a road marking machine, which can adjust the marking widths according to the lane type.[15]

Traffic reports in California often refer to accidents being "in the number X lane." The California Department of Transportation (Caltrans) assigns the numbers from left to right.[16] The far left passing lane is the number 1 lane. The number of the slow lane (closest to freeway onramps/offramps) depends on the total number of lanes, and could be anywhere from 2 to 8.

For much of human history, roads did not need lane markings because most people walked or rode horses at relatively slow speeds. Another reason for not using lane markings is that they are expensive to maintain.

When automobiles, trucks, and buses came into widespread use during the first two decades of the 20th century, head-on collisions became more common.

Without the guidance provided by lane markings, drivers in the early days often erred in favor of keeping closer to the middle of the road, rather than risk going off-road into ditches or trees[citation needed]. This practice often left inadequate room for opposing traffic.

The history of lane markings is connected to the mass automobile construction in Detroit. It resulted in the formation of the first Road Commission of Wayne County, Michigan in 1906 which was trying to make roads safer (Henry Ford served on the board in the first year).[17] The commission would order the construction of the first concrete road in 1909 (the Woodard Avenue in Detroit) and it conceived the centerline for highways in 1911. Hence the chairmen of the Road Commission, Edward N. Hines is widely credited as the inventor of line markings.[18]

The introduction as a common standard is connected to June McCarroll, a physician in Indio, California who started experimenting with painting lines on roads in 1917 after she was run off a highway by a truck driver. In November 1924, after years of lobbying by Dr. McCarroll and her allies, California officially adopted a policy of painting lines on its highways. A portion of Interstate 10 near Indio has been named the Dr. June McCarroll Memorial Freeway in her honor.

black center line on an Autobahn in Germany (late 1930s)

The first lane markings in Europe were painted at an accident hotspot in the small town of Sutton Coldfield near Birmingham, England in 1921. The success of this experiment made its way to other hotspots and later standardization of white paint for line markings in Great Britain.[19]

The first lane markings in Germany were used in Berlin in 1925 using white paint for line markings and road edge markings. When the standard for the new autobahn network was conceived in the 1930s it mandated the usage of black paint for the center line for each carriageway as black was better visible on the bright surface of the concrete roads.

By 1939, lane markings had become so popular that they were officially standardized throughout the United States. The concept of line markings spread throughout the world becoming standard for most roads. Originally the lines were drawn manually with normal paint which would bleach out quickly. After the war, the first machines for line markings were invented[20] and a plastic strip was becoming standard in the 1950s which led to gradually find line markings on all roads.

Main article: Right- and left-hand traffic

Lane

Pave My Driveway Costs Not to be confused with cement or mortar (masonry). Exterior of the Roman Pantheon, finished 128 AD, the largest unreinforced concrete dome in the world.[1] Interior of the Pantheon dome, seen from beneath. The concrete for the coffered dome was laid on moulds, probably mounted on temporary scaffolding. Opus caementicium exposed in a characteristic Roman arch. In contrast to modern concrete structures, the concrete used in Roman buildings was usually covered with brick or stone.

Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens over time. Most concretes used are lime-based concretes such as Portland cement concrete or concretes made with other hydraulic cements, such as calcium aluminate cements. However, asphalt concrete, which is frequently used for road surfaces, is also a type of concrete, where the cement material is bitumen, and polymer concretes are sometimes used where the cementing material is a polymer.

When aggregate is mixed together with dry Portland cement and water, the mixture forms a fluid slurry that is easily poured and molded into shape. The cement reacts chemically with the water and other ingredients to form a hard matrix that binds the materials together into a durable stone-like material that has many uses.[2] Often, additives (such as pozzolans or superplasticizers) are included in the mixture to improve the physical properties of the wet mix or the finished material. Most concrete is poured with reinforcing materials (such as rebar) embedded to provide tensile strength, yielding reinforced concrete.

Famous concrete structures include the Hoover Dam, the Panama Canal, and the Roman Pantheon. The earliest large-scale users of concrete technology were the ancient Romans, and concrete was widely used in the Roman Empire. The Colosseum in Rome was built largely of concrete, and the concrete dome of the Pantheon is the world's largest unreinforced concrete dome.[3] Today, large concrete structures (for example, dams and multi-storey car parks) are usually made with reinforced concrete.

After the Roman Empire collapsed, use of concrete became rare until the technology was redeveloped in the mid-18th century. Today, concrete is the most widely used human-made material (measured by tonnage).[citation needed]

The word concrete comes from the Latin word "concretus" (meaning compact or condensed),[4] the perfect passive participle of "concrescere", from "con-" (together) and "crescere" (to grow).

Small-scale usage of concrete has been documented to be thousands of years old. Concrete-like materials were used since 6500 BC by the Nabataea traders or Bedouins, who occupied and controlled a series of oases and developed a small empire in the regions of southern Syria and northern Jordan. They discovered the advantages of hydraulic lime, with some self-cementing properties, by 700 BC. They built kilns to supply mortar for the construction of rubble-wall houses, concrete floors, and underground waterproof cisterns. They kept the cisterns secret as these enabled the Nabataea to thrive in the desert.[5] Some of these structures survive to this day.[5]

In the Ancient Egyptian and later Roman eras, builders re-discovered that adding volcanic ash to the mix allowed it to set underwater.

German archaeologist Heinrich Schliemann found concrete floors, which were made of lime and pebbles, in the royal palace of Tiryns, Greece, which dates roughly to 1400–1200 BC.[6][7] Lime mortars were used in Greece, Crete, and Cyprus in 800 BC. The Assyrian Jerwan Aqueduct (688 BC) made use of waterproof concrete.[8] Concrete was used for construction in many ancient structures.[9]

The Romans used concrete extensively from 300 BC to 476 AD, a span of more than seven hundred years.[10] During the Roman Empire, Roman concrete (or opus caementicium) was made from quicklime, pozzolana and an aggregate of pumice. Its widespread use in many Roman structures, a key event in the history of architecture termed the Roman Architectural Revolution, freed Roman construction from the restrictions of stone and brick materials. It enabled revolutionary new designs in terms of both structural complexity and dimension.[11]

Concrete, as the Romans knew it, was a new and revolutionary material. Laid in the shape of arches, vaults and domes, it quickly hardened into a rigid mass, free from many of the internal thrusts and strains that troubled the builders of similar structures in stone or brick.[12]

Modern tests show that opus caementicium had as much compressive strength as modern Portland-cement concrete (ca. 200 kg/cm2 [20 MPa; 2,800 psi]).[13] However, due to the absence of reinforcement, its tensile strength was far lower than modern reinforced concrete, and its mode of application was also different:[14]

Modern structural concrete differs from Roman concrete in two important details. First, its mix consistency is fluid and homogeneous, allowing it to be poured into forms rather than requiring hand-layering together with the placement of aggregate, which, in Roman practice, often consisted of rubble. Second, integral reinforcing steel gives modern concrete assemblies great strength in tension, whereas Roman concrete could depend only upon the strength of the concrete bonding to resist tension.[15]

The long-term durability of Roman concrete structures has been found to be due to its use of pyroclastic (volcanic) rock and ash, whereby crystallization of strätlingite and the coalescence of calcium–aluminum-silicate–hydrate cementing binder helped give the concrete a greater degree of fracture resistance even in seismically active environments.[16] Roman concrete is significantly more resistant to erosion by seawater than modern concrete; it used pyroclastic materials which react with seawater to form Al-tobermorite crystals over time.[17][18]

Smeaton's Tower

The widespread use of concrete in many Roman structures ensured that many survive to the present day. The Baths of Caracalla in Rome are just one example. Many Roman aqueducts and bridges, such as the magnificent Pont du Gard in southern France, have masonry cladding on a concrete core, as does the dome of the Pantheon.

After the Roman Empire, the use of burned lime and pozzolana was greatly reduced until the technique was all but forgotten between 500 and the 14th century. From the 14th century to the mid-18th century, the use of cement gradually returned. The Canal du Midi was built using concrete in 1670.[19]

Perhaps the greatest driver behind the modern use of concrete was Smeaton's Tower, the third Eddystone Lighthouse in Devon, England. To create this structure, between 1756 and 1759, British engineer John Smeaton pioneered the use of hydraulic lime in concrete, using pebbles and powdered brick as aggregate.[20]

Developed in England in the 19th century, a method for producing Portland cement was patented by Joseph Aspdin in 1824.[21] Aspdin named it due to its similarity to Portland stone which was quarried on the Isle of Portland in Dorset, England. His son William Aspdin is regarded as the inventor of "modern" Portland cement due to his developments in the 1840s.[22]

Reinforced concrete was invented in 1849 by Joseph Monier.[23] In 1889 the first concrete reinforced bridge was built, and the first large concrete dams were built in 1936, Hoover Dam and Grand Coulee Dam.[24]

Many types of concrete are available, distinguished by the proportions of the main ingredients below. In this way or by substitution for the cementitious and aggregate phases, the finished product can be tailored to its application. Strength, density, as well chemical and thermal resistance are variables.

Aggregate consists of large chunks of material in a concrete mix, generally a coarse gravel or crushed rocks such as limestone, or granite, along with finer materials such as sand.

Cement, most commonly Portland cement, is associated with the general term "concrete." A range of other materials can be used as the cement in concrete too. One of the most familiar of these alternative cements is asphalt concrete. Other cementitious materials such as fly ash and slag cement, are sometimes added as mineral admixtures (see below) - either pre-blended with the cement or directly as a concrete component - and become a part of the binder for the aggregate.

To produce concrete from most cements (excluding asphalt), water is mixed with the dry powder and aggregate, which produces a semi-liquid slurry that can be shaped, typically by pouring it into a form. The concrete solidifies and hardens through a chemical process called hydration. The water reacts with the cement, which bonds the other components together, creating a robust stone-like material.

Chemical admixtures are added to achieve varied properties. These ingredients may accelerate or slow down the rate at which the concrete hardens, and impart many other useful properties including increased tensile strength, entrainment of air and water resistance.

Reinforcement is often included in concrete. Concrete can be formulated with high compressive strength, but always has lower tensile strength. For this reason it is usually reinforced with materials that are strong in tension, typically steel rebar.

Mineral admixtures have become more popular over recent decades. The use of recycled materials as concrete ingredients has been gaining popularity because of increasingly stringent environmental legislation, and the discovery that such materials often have complementary and valuable properties. The most conspicuous of these are fly ash, a by-product of coal-fired power plants, ground granulated blast furnace slag, a byproduct of steelmaking, and silica fume, a byproduct of industrial electric arc furnaces. The use of these materials in concrete reduces the amount of resources required, as the mineral admixtures act as a partial cement replacement. This displaces some cement production, an energetically expensive and environmentally problematic process, while reducing the amount of industrial waste that must be disposed of. Mineral admixtures can be pre-blended with the cement during its production for sale and use as a blended cement, or mixed directly with other components when the concrete is produced.

The mix design depends on the type of structure being built, how the concrete is mixed and delivered, and how it is placed to form the structure.

Main article: Cement A few tons of bagged cement. This amount represents about two minutes of output from a 10,000 ton per day cement kiln.

Portland cement is the most common type of cement in general usage. It is a basic ingredient of concrete, mortar and many plasters. British masonry worker Joseph Aspdin patented Portland cement in 1824. It was named because of the similarity of its colour to Portland limestone, quarried from the English Isle of Portland and used extensively in London architecture. It consists of a mixture of calcium silicates (alite, belite), aluminates and ferrites - compounds which combine calcium, silicon, aluminium and iron in forms which will react with water. Portland cement and similar materials are made by heating limestone (a source of calcium) with clay or shale (a source of silicon, aluminium and iron) and grinding this product (called clinker) with a source of sulfate (most commonly gypsum).

In modern cement kilns many advanced features are used to lower the fuel consumption per ton of clinker produced. Cement kilns are extremely large, complex, and inherently dusty industrial installations, and have emissions which must be controlled. Of the various ingredients used to produce a given quantity of concrete, the cement is the most energetically expensive. Even complex and efficient kilns require 3.3 to 3.6 gigajoules of energy to produce a ton of clinker and then grind it into cement. Many kilns can be fueled with difficult-to-dispose-of wastes, the most common being used tires. The extremely high temperatures and long periods of time at those temperatures allows cement kilns to efficiently and completely burn even difficult-to-use fuels.[25]

Combining water with a cementitious material forms a cement paste by the process of hydration. The cement paste glues the aggregate together, fills voids within it, and makes it flow more freely.[26]

As stated by Abrams' law, a lower water-to-cement ratio yields a stronger, more durable concrete, whereas more water gives a freer-flowing concrete with a higher slump.[27] Impure water used to make concrete can cause problems when setting or in causing premature failure of the structure.[28]

Hydration involves many different reactions, often occurring at the same time. As the reactions proceed, the products of the cement hydration process gradually bond together the individual sand and gravel particles and other components of the concrete to form a solid mass.[29]

Reaction:[29]

Cement chemist notation: C3S + H → C-S-H + CH Standard notation: Ca3SiO5 + H2O → (CaO)·(SiO2)·(H2O)(gel) + Ca(OH)2 Balanced: 2Ca3SiO5 + 7H2O → 3(CaO)·2(SiO2)·4(H2O)(gel) + 3Ca(OH)2 (approximately; the exact ratios of the CaO, SiO2 and H2O in C-S-H can vary) Crushed stone aggregate Main article: Construction aggregate

Fine and coarse aggregates make up the bulk of a concrete mixture. Sand, natural gravel, and crushed stone are used mainly for this purpose. Recycled aggregates (from construction, demolition, and excavation waste) are increasingly used as partial replacements for natural aggregates, while a number of manufactured aggregates, including air-cooled blast furnace slag and bottom ash are also permitted.

The size distribution of the aggregate determines how much binder is required. Aggregate with a very even size distribution has the biggest gaps whereas adding aggregate with smaller particles tends to fill these gaps. The binder must fill the gaps between the aggregate as well as pasting the surfaces of the aggregate together, and is typically the most expensive component. Thus variation in sizes of the aggregate reduces the cost of concrete.[30] The aggregate is nearly always stronger than the binder, so its use does not negatively affect the strength of the concrete.

Redistribution of aggregates after compaction often creates inhomogeneity due to the influence of vibration. This can lead to strength gradients.[31]

Decorative stones such as quartzite, small river stones or crushed glass are sometimes added to the surface of concrete for a decorative "exposed aggregate" finish, popular among landscape designers.

In addition to being decorative, exposed aggregate may add robustness to a concrete.[32]

Constructing a rebar cage. This cage will be permanently embedded in poured concrete to create a reinforced concrete structure. Main article: Reinforced concrete

Concrete is strong in compression, as the aggregate efficiently carries the compression load. However, it is weak in tension as the cement holding the aggregate in place can crack, allowing the structure to fail. Reinforced concrete adds either steel reinforcing bars, steel fibers, glass fibers, or plastic fibers to carry tensile loads.

Chemical admixtures are materials in the form of powder or fluids that are added to the concrete to give it certain characteristics not obtainable with plain concrete mixes. In normal use, admixture dosages are less than 5% by mass of cement and are added to the concrete at the time of batching/mixing.[33] (See the section on Concrete Production, below.)The common types of admixtures[34] are as follows:

Inorganic materials that have pozzolanic or latent hydraulic properties, these very fine-grained materials are added to the concrete mix to improve the properties of concrete (mineral admixtures),[33] or as a replacement for Portland cement (blended cements).[39] Products which incorporate limestone, fly ash, blast furnace slag, and other useful materials with pozzolanic properties into the mix, are being tested and used. This development is due to cement production being one of the largest producers (at about 5 to 10%) of global greenhouse gas emissions,[40] as well as lowering costs, improving concrete properties, and recycling wastes.

Concrete plant facility showing a Concrete mixer being filled from the ingredient silos.

Concrete production is the process of mixing together the various ingredients—water, aggregate, cement, and any additives—to produce concrete. Concrete production is time-sensitive. Once the ingredients are mixed, workers must put the concrete in place before it hardens. In modern usage, most concrete production takes place in a large type of industrial facility called a concrete plant, or often a batch plant.

In general usage, concrete plants come in two main types, ready mix plants and central mix plants. A ready mix plant mixes all the ingredients except water, while a central mix plant mixes all the ingredients including water. A central mix plant offers more accurate control of the concrete quality through better measurements of the amount of water added, but must be placed closer to the work site where the concrete will be used, since hydration begins at the plant.

A concrete plant consists of large storage hoppers for various reactive ingredients like cement, storage for bulk ingredients like aggregate and water, mechanisms for the addition of various additives and amendments, machinery to accurately weigh, move, and mix some or all of those ingredients, and facilities to dispense the mixed concrete, often to a concrete mixer truck.

Modern concrete is usually prepared as a viscous fluid, so that it may be poured into forms, which are containers erected in the field to give the concrete its desired shape. Concrete formwork can be prepared in several ways, such as Slip forming and Steel plate construction. Alternatively, concrete can be mixed into dryer, non-fluid forms and used in factory settings to manufacture Precast concrete products.

A wide variety of equipment is used for processing concrete, from hand tools to heavy industrial machinery. Whichever equipment builders use, however, the objective is to produce the desired building material; ingredients must be properly mixed, placed, shaped, and retained within time constraints. Any interruption in pouring the concrete can cause the initially placed material to begin to set before the next batch is added on top. This creates a horizontal plane of weakness called a cold joint between the two batches.[46] Once the mix is where it should be, the curing process must be controlled to ensure that the concrete attains the desired attributes. During concrete preparation, various technical details may affect the quality and nature of the product.

When initially mixed, Portland cement and water rapidly form a gel of tangled chains of interlocking crystals, and components of the gel continue to react over time. Initially the gel is fluid, which improves workability and aids in placement of the material, but as the concrete sets, the chains of crystals join into a rigid structure, counteracting the fluidity of the gel and fixing the particles of aggregate in place. During curing, the cement continues to react with the residual water in a process of hydration. In properly formulated concrete, once this curing process has terminated the product has the desired physical and chemical properties. Among the qualities typically desired, are mechanical strength, low moisture permeability, and chemical and volumetric stability.

See also: Volumetric concrete mixer and Concrete mixer

Thorough mixing is essential for the production of uniform, high-quality concrete. For this reason equipment and methods should be capable of effectively mixing concrete materials containing the largest specified aggregate to produce uniform mixtures of the lowest slump practical for the work.

Separate paste mixing has shown that the mixing of cement and water into a paste before combining these materials with aggregates can increase the compressive strength of the resulting concrete.[47] The paste is generally mixed in a high-speed, shear-type mixer at a w/cm (water to cement ratio) of 0.30 to 0.45 by mass. The cement paste premix may include admixtures such as accelerators or retarders, superplasticizers, pigments, or silica fume. The premixed paste is then blended with aggregates and any remaining batch water and final mixing is completed in conventional concrete mixing equipment.[48]

Decorative plate made of Nano concrete with High-Energy Mixing (HEM) Pouring and smoothing out concrete at Palisades Park in Washington DC. Main article: Concrete slump test

Workability is the ability of a fresh (plastic) concrete mix to fill the form/mold properly with the desired work (vibration) and without reducing the concrete's quality. Workability depends on water content, aggregate (shape and size distribution), cementitious content and age (level of hydration) and can be modified by adding chemical admixtures, like superplasticizer. Raising the water content or adding chemical admixtures increases concrete workability. Excessive water leads to increased bleeding or segregation of aggregates (when the cement and aggregates start to separate), with the resulting concrete having reduced quality. The use of an aggregate blend with an undesirable gradation[49] can result in a very harsh mix design with a very low slump, which cannot readily be made more workable by addition of reasonable amounts of water. An undesirable gradation can mean using a large aggregate that is too large for the size of the formwork, or which has too few smaller aggregate grades to serve to fill the gaps between the larger grades, or using too little or too much sand for the same reason, or using too little water, or too much cement, or even using jagged crushed stone instead of smoother round aggregate such as pebbles. Any combination of these factors and others may result in a mix which is too harsh, i.e., which does not flow or spread out smoothly, is difficult to get into the formwork, and which is difficult to surface finish.[50]

Workability can be measured by the concrete slump test, a simple measure of the plasticity of a fresh batch of concrete following the ASTM C 143 or EN 12350-2 test standards. Slump is normally measured by filling an "Abrams cone" with a sample from a fresh batch of concrete. The cone is placed with the wide end down onto a level, non-absorptive surface. It is then filled in three layers of equal volume, with each layer being tamped with a steel rod to consolidate the layer. When the cone is carefully lifted off, the enclosed material slumps a certain amount, owing to gravity. A relatively dry sample slumps very little, having a slump value of one or two inches (25 or 50 mm) out of one foot (305 mm). A relatively wet concrete sample may slump as much as eight inches. Workability can also be measured by the flow table test.

Slump can be increased by addition of chemical admixtures such as plasticizer or superplasticizer without changing the water-cement ratio.[51] Some other admixtures, especially air-entraining admixture, can increase the slump of a mix.

High-flow concrete, like self-consolidating concrete, is tested by other flow-measuring methods. One of these methods includes placing the cone on the narrow end and observing how the mix flows through the cone while it is gradually lifted.

After mixing, concrete is a fluid and can be pumped to the location where needed.

A concrete slab ponded while curing.

A common misconception is that concrete dries as it sets, but the opposite is true - damp concrete sets better than dry concrete. In other words, "hydraulic cement" needs water to become strong. Too much water is counterproductive, but too little water is deleterious. Curing allows concrete to achieve optimal strength and hardness.[52] Curing is the hydration process that occurs after the concrete has been placed. In chemical terms, curing allows calcium-silicate hydrate (C-S-H) to form. To gain strength and harden fully, concrete curing requires time. In around 4 weeks, typically over 90% of the final strength is reached, although strengthening may continue for decades.[53] The conversion of calcium hydroxide in the concrete into calcium carbonate from absorption of CO2 over several decades further strengthens the concrete and makes it more resistant to damage. This carbonation reaction, however, lowers the pH of the cement pore solution and can corrode the reinforcement bars.

Hydration and hardening of concrete during the first three days is critical. Abnormally fast drying and shrinkage due to factors such as evaporation from wind during placement may lead to increased tensile stresses at a time when it has not yet gained sufficient strength, resulting in greater shrinkage cracking. The early strength of the concrete can be increased if it is kept damp during the curing process. Minimizing stress prior to curing minimizes cracking. High-early-strength concrete is designed to hydrate faster, often by increased use of cement that increases shrinkage and cracking. The strength of concrete changes (increases) for up to three years. It depends on cross-section dimension of elements and conditions of structure exploitation.[54] Addition of short-cut polymer fibers can improve (reduce) shrinkage-induced stresses during curing and increase early and ultimate compression strength.[55]

Properly curing concrete leads to increased strength and lower permeability and avoids cracking where the surface dries out prematurely. Care must also be taken to avoid freezing or overheating due to the exothermic setting of cement. Improper curing can cause scaling, reduced strength, poor abrasion resistance and cracking.

During the curing period, concrete is ideally maintained at controlled temperature and humidity. To ensure full hydration during curing, concrete slabs are often sprayed with "curing compounds" that create a water-retaining film over the concrete. Typical films are made of wax or related hydrophobic compounds. After the concrete is sufficiently cured, the film is allowed to abrade from the concrete through normal use.[56]

Traditional conditions for curing involve by spraying or ponding the concrete surface with water. The picture to the right shows one of many ways to achieve this, ponding – submerging setting concrete in water and wrapping in plastic to prevent dehydration. Additional common curing methods include wet burlap and plastic sheeting covering the fresh concrete.

For higher-strength applications, accelerated curing techniques may be applied to the concrete. One common technique involves heating the poured concrete with steam, which serves to both keep it damp and raise the temperature, so that the hydration process proceeds more quickly and more thoroughly.

Main article: Pervious concrete

Pervious concrete is a mix of specially graded coarse aggregate, cement, water and little-to-no fine aggregates. This concrete is also known as "no-fines" or porous concrete. Mixing the ingredients in a carefully controlled process creates a paste that coats and bonds the aggregate particles. The hardened concrete contains interconnected air voids totalling approximately 15 to 25 percent. Water runs through the voids in the pavement to the soil underneath. Air entrainment admixtures are often used in freeze–thaw climates to minimize the possibility of frost damage.

Two-layered pavers, top layer made of pigmented HEM Nanoconcrete.

Nanoconcrete is created by high-energy mixing (HEM) of cement, sand and water. To ensure the mixing is thorough enough to create nano-concrete, the mixer must apply a total mixing power to the mixture of 30 - 600 watts per kilogram of the mix. This mixing must continue long enough to yield a net specific energy expended upon the mix of at least 5000 joules per kilogram of the mix.[57] A plasticizer or a superplasticizer is then added to the activated mixture which can later be mixed with aggregates in a conventional concrete mixer. In the HEM process, the intense mixing of cement and water with sand provides dissipation of energy and increases shear stresses on the surface of cement particles. This intense mixing serves to divide the cement particles into extremely fine nanometer scale sizes, which provides for extremely thorough mixing. This results in the increased volume of water interacting with cement and acceleration of Calcium Silicate Hydrate (C-S-H) colloid creation.

The initial natural process of cement hydration with formation of colloidal globules about 5 nm in diameter[58] spreads into the entire volume of cement – water matrix as the energy expended upon the mix approaches and exceeds 5000 joules per kilogram.

The liquid activated high-energy mixture can be used by itself for casting small architectural details and decorative items, or foamed (expanded) for lightweight concrete. HEM Nanoconcrete hardens in low and subzero temperature conditions and possesses an increased volume of gel, which reduces capillarity in solid and porous materials.

Bacteria such as Bacillus pasteurii, Bacillus pseudofirmus, Bacillus cohnii, Sporosarcina pasteuri, and Arthrobacter crystallopoietes increase the compression strength of concrete through their biomass. Not all bacteria increase the strength of concrete significantly with their biomass.[59]:143 Bacillus sp. CT-5. can reduce corrosion of reinforcement in reinforced concrete by up to four times. Sporosarcina pasteurii reduces water and chloride permeability. B. pasteurii increases resistance to acid.[59]:146 Bacillus pasteurii and B. sphaericuscan induce calcium carbonate precipitation in the surface of cracks, adding compression strength.[59]:147

Main article: Polymer concrete

Polymer concretes are mixtures of aggregate and any of various polymers and may be reinforced. The cement is more costly than lime-based cements, but polymer concretes nevertheless have advantages, they have significant tensile strength even without reinforcement, and they are largely impervious to water. They are frequently used for repair and construction of other applications such as drains.

Concrete, when ground, can result in the creation of hazardous dust. The National Institute for Occupational Safety and Health in the United States recommends attaching local exhaust ventilation shrouds to electric concrete grinders to control the spread of this dust.[60]

Main article: Properties of concrete

Concrete has relatively high compressive strength, but much lower tensile strength. For this reason it is usually reinforced with materials that are strong in tension (often steel). The elasticity of concrete is relatively constant at low stress levels but starts decreasing at higher stress levels as matrix cracking develops. Concrete has a very low coefficient of thermal expansion and shrinks as it matures. All concrete structures crack to some extent, due to shrinkage and tension. Concrete that is subjected to long-duration forces is prone to creep.

Tests can be performed to ensure that the properties of concrete correspond to specifications for the application.

Compression testing of a concrete cylinder

Different mixes of concrete ingredients produce different strengths. Concrete strength values are usually specified as the lower-bound compressive strength of either a cylindrical or cubic specimen as determined by standard test procedures.

Different strengths of concrete are used for different purposes. Very low-strength - 14 MPa (2,000 psi) or less - concrete may be used when the concrete must be lightweight.[61] Lightweight concrete is often achieved by adding air, foams, or lightweight aggregates, with the side effect that the strength is reduced. For most routine uses, 20 MPa (2,900 psi) to 32 MPa (4,600 psi) concrete is often used. 40 MPa (5,800 psi) concrete is readily commercially available as a more durable, although more expensive, option. Higher-strength concrete is often used for larger civil projects.[62] Strengths above 40 MPa (5,800 psi) are often used for specific building elements. For example, the lower floor columns of high-rise concrete buildings may use concrete of 80 MPa (11,600 psi) or more, to keep the size of the columns small. Bridges may use long beams of high-strength concrete to lower the number of spans required.[63][64] Occasionally, other structural needs may require high-strength concrete. If a structure must be very rigid, concrete of very high strength may be specified, even much stronger than is required to bear the service loads. Strengths as high as 130 MPa (18,900 psi) have been used commercially for these reasons.[63]

The Buffalo City Court Building in Buffalo, NY.

Concrete is one of the most durable building materials. It provides superior fire resistance compared with wooden construction and gains strength over time. Structures made of concrete can have a long service life. Concrete is used more than any other human-made material in the world.[65] As of 2006, about 7.5 billion cubic meters of concrete are made each year, more than one cubic meter for every person on Earth.[66]

Main article: Mass concrete Aerial photo of reconstruction at Taum Sauk (Missouri) pumped storage facility in late November, 2009. After the original reservoir failed, the new reservoir was made of roller-compacted concrete.

Due to cement's exothermic chemical reaction while setting up, large concrete structures such as dams, navigation locks, large mat foundations, and large breakwaters generate excessive heat during hydration and associated expansion. To mitigate these effects post-cooling[67] is commonly applied during construction. An early example at Hoover Dam, installed a network of pipes between vertical concrete placements to circulate cooling water during the curing process to avoid damaging overheating. Similar systems are still used; depending on volume of the pour, the concrete mix used, and ambient air temperature, the cooling process may last for many months after the concrete is placed. Various methods also are used to pre-cool the concrete mix in mass concrete structures.[67]

Another approach to mass concrete structures that minimizes cement's thermal byproduct is the use of roller-compacted concrete, which uses a dry mix which has a much lower cooling requirement than conventional wet placement. It is deposited in thick layers as a semi-dry material then roller compacted into a dense, strong mass.

Main article: Decorative concrete Black basalt polished concrete floor

Raw concrete surfaces tend to be porous, and have a relatively uninteresting appearance. Many different finishes can be applied to improve the appearance and preserve the surface against staining, water penetration, and freezing.

Examples of improved appearance include stamped concrete where the wet concrete has a pattern impressed on the surface, to give a paved, cobbled or brick-like effect, and may be accompanied with coloration. Another popular effect for flooring and table tops is polished concrete where the concrete is polished optically flat with diamond abrasives and sealed with polymers or other sealants.

Other finishes can be achieved with chiselling, or more conventional techniques such as painting or covering it with other materials.

The proper treatment of the surface of concrete, and therefore its characteristics, is an important stage in the construction and renovation of architectural structures.[68]

40-foot cacti decorate a sound/retaining wall in Scottsdale, Arizona Main article: Prestressed concrete

Prestressed concrete is a form of reinforced concrete that builds in compressive stresses during construction to oppose those experienced in use. This can greatly reduce the weight of beams or slabs, by better distributing the stresses in the structure to make optimal use of the reinforcement. For example, a horizontal beam tends to sag. Prestressed reinforcement along the bottom of the beam counteracts this. In pre-tensioned concrete, the prestressing is achieved by using steel or polymer tendons or bars that are subjected to a tensile force prior to casting, or for post-tensioned concrete, after casting.

More than 55,000 miles (89,000 km) of highways in the United States are paved with this material. Reinforced concrete, prestressed concrete and precast concrete are the most widely used types of concrete functional extensions in modern days. See Brutalism.

Extreme weather conditions (extreme heat or cold; windy condition, and humidity variations) can significantly alter the quality of concrete. In cold weather concreting, many precautions are observed.[69] Low temperatures significantly slow the chemical reactions involved in hydration of cement, thus affecting the strength development. Preventing freezing is the most important precaution, as formation of ice crystals can cause damage to the crystalline structure of the hydrated cement paste. If the surface of the concrete pour is insulated from the outside temperatures, the heat of hydration will prevent freezing.

The American Concrete Institute (ACI) definition of cold weather concreting, ACI 306,[70] is:

In Canada, where temperatures tend to be much lower during the cold season, the following criteria is used by CSA A23.1:

The minimum strength before exposing concrete to extreme cold is 500 psi (3.5 MPa). CSA A 23.1 specified a compressive strength of 7.0 MPa to be considered safe for exposure to freezing.

Concrete roads are more fuel efficient to drive on,[71] more reflective and last significantly longer than other paving surfaces, yet have a much smaller market share than other paving solutions. Modern-paving methods and design practices have changed the economics of concrete paving, so that a well-designed and placed concrete pavement will be less expensive on initial costs and significantly less expensive over the life cycle. Another major benefit is that pervious concrete can be used, which eliminates the need to place storm drains near the road, and reducing the need for slightly sloped roadway to help rainwater to run off. No longer requiring discarding rainwater through use of drains also means that less electricity is needed (more pumping is otherwise needed in the water-distribution system), and no rainwater gets polluted as it no longer mixes with polluted water. Rather, it is immediately absorbed by the ground.

Energy requirements for transportation of concrete are low because it is produced locally from local resources, typically manufactured within 100 kilometers of the job site. Similarly, relatively little energy is used in producing and combining the raw materials (although large amounts of CO2 are produced by the chemical reactions in cement manufacture).[72] The overall embodied energy of concrete at roughly 1 to 1.5 megajoules per kilogram is therefore lower than for most structural and construction materials.[73]

Once in place, concrete offers great energy efficiency over the lifetime of a building.[74] Concrete walls leak air far less than those made of wood frames.[75] Air leakage accounts for a large percentage of energy loss from a home. The thermal mass properties of concrete increase the efficiency of both residential and commercial buildings. By storing and releasing the energy needed for heating or cooling, concrete's thermal mass delivers year-round benefits by reducing temperature swings inside and minimizing heating and cooling costs.[76] While insulation reduces energy loss through the building envelope, thermal mass uses walls to store and release energy. Modern concrete wall systems use both external insulation and thermal mass to create an energy-efficient building. Insulating concrete forms (ICFs) are hollow blocks or panels made of either insulating foam or rastra that are stacked to form the shape of the walls of a building and then filled with reinforced concrete to create the structure.

A modern building: Boston City Hall (completed 1968) is constructed largely of concrete, both precast and poured in place. Of Brutalist architecture, it was voted "The World's Ugliest Building" in 2008.

Concrete buildings are more resistant to fire than those constructed using steel frames, since concrete has lower heat conductivity than steel and can thus last longer under the same fire conditions. Concrete is sometimes used as a fire protection for steel frames, for the same effect as above. Concrete as a fire shield, for example Fondu fyre, can also be used in extreme environments like a missile launch pad.

Options for non-combustible construction include floors, ceilings and roofs made of cast-in-place and hollow-core precast concrete. For walls, concrete masonry technology and Insulating Concrete Forms (ICFs) are additional options. ICFs are hollow blocks or panels made of fireproof insulating foam that are stacked to form the shape of the walls of a building and then filled with reinforced concrete to create the structure.

Concrete also provides good resistance against externally applied forces such as high winds, hurricanes, and tornadoes owing to its lateral stiffness, which results in minimal horizontal movement. However this stiffness can work against certain types of concrete structures, particularly where a relatively higher flexing structure is required to resist more extreme forces.

As discussed above, concrete is very strong in compression, but weak in tension. Larger earthquakes can generate very large shear loads on structures. These shear loads subject the structure to both tensile and compressional loads. Concrete structures without reinforcement, like other unreinforced masonry structures, can fail during severe earthquake shaking. Unreinforced masonry structures constitute one of the largest earthquake risks globally.[77] These risks can be reduced through seismic retrofitting of at-risk buildings, (e.g. school buildings in Istanbul, Turkey[78]).

Concrete spalling caused by the corrosion of rebar Main article: Concrete degradation

Concrete can be damaged by many processes, such as the expansion of corrosion products of the steel reinforcement bars, freezing of trapped water, fire or radiant heat, aggregate expansion, sea water effects, bacterial corrosion, leaching, erosion by fast-flowing water, physical damage and chemical damage (from carbonatation, chlorides, sulfates and distillate water).[citation needed] The micro fungi Aspergillus Alternaria and Cladosporium were able to grow on samples of concrete used as a radioactive waste barrier in the Chernobyl reactor; leaching aluminium, iron, calcium and silicon.[79]

The Tunkhannock Viaduct began service in 1912 and is still in regular use more than 100 years later.

Concrete can be viewed as a form of artificial sedimentary rock. As a type of mineral, the compounds of which it is composed are extremely stable.[80] Many concrete structures are built with an expected lifetime of approximately 100 years,[81] but researchers have suggested that adding silica fume could extend the useful life of bridges and other concrete uses to as long as 16,000 years.[82] Coatings are also available to protect concrete from damage, and extend the useful life. Epoxy coatings may be applied only to interior surfaces, though, as they would otherwise trap moisture in the concrete.[83]

A self-healing concrete has been developed that can also last longer than conventional concrete.[84] Another option is to use hydrophobic concrete.

Concrete mixing plant in Birmingham, Alabama in 1936

Concrete is widely used for making architectural structures, foundations, brick/block walls, pavements, bridges/overpasses, highways, runways, parking structures, dams, pools/reservoirs, pipes, footings for gates, fences and poles and even boats. Concrete is used in large quantities almost everywhere mankind has a need for infrastructure. Concrete is one of the most frequently used building materials in animal houses and for manure and silage storage structures in agriculture.[85]

The amount of concrete used worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminum combined. Concrete's use in the modern world is exceeded only by that of naturally occurring water.[86]

Concrete is also the basis of a large commercial industry. Globally, the ready-mix concrete industry, the largest segment of the concrete market, is projected to exceed $100 billion in revenue by 2015.[87] In the United States alone, concrete production is a $30-billion-per-year industry, considering only the value of the ready-mixed concrete sold each year.[88] Given the size of the concrete industry, and the fundamental way concrete is used to shape the infrastructure of the modern world, it is difficult to overstate the role this material plays today.

Main article: Environmental impact of concrete

The manufacture and use of concrete produce a wide range of environmental and social consequences. Some are harmful, some welcome, and some both, depending on circumstances.

A major component of concrete is cement, which similarly exerts environmental and social effects.[59]:142 The cement industry is one of the three primary producers of carbon dioxide, a major greenhouse gas (the other two being the energy production and transportation industries). As of 2001, the production of Portland cement contributed 7% to global anthropogenic CO2 emissions, largely due to the sintering of limestone and clay at 1,500 °C (2,730 °F).[89]

Concrete is used to create hard surfaces that contribute to surface runoff, which can cause heavy soil erosion, water pollution, and flooding, but conversely can be used to divert, dam, and control flooding.

Concrete is a contributor to the urban heat island effect, though less so than asphalt.[90]

Workers who cut, grind or polish concrete are at risk of inhaling airborne silica, which can lead to silicosis.[91] Concrete dust released by building demolition and natural disasters can be a major source of dangerous air pollution.

The presence of some substances in concrete, including useful and unwanted additives, can cause health concerns due to toxicity and radioactivity. Fresh concrete (before curing is complete) is highly alkaline and must be handled with proper protective equipment.

Recycled crushed concrete, to be reused as granular fill, is loaded into a semi-dump truck. Main article: Concrete recycling

Concrete recycling is an increasingly common method for disposing of concrete structures. Concrete debris was once routinely shipped to landfills for disposal, but recycling is increasing due to improved environmental awareness, governmental laws and economic benefits.

Concrete, which must be free of trash, wood, paper and other such materials, is collected from demolition sites and put through a crushing machine, often along with asphalt, bricks and rocks.

Reinforced concrete contains rebar and other metallic reinforcements, which are removed with magnets and recycled elsewhere. The remaining aggregate chunks are sorted by size. Larger chunks may go through the crusher again. Smaller pieces of concrete are used as gravel for new construction projects. Aggregate base gravel is laid down as the lowest layer in a road, with fresh concrete or asphalt placed over it. Crushed recycled concrete can sometimes be used as the dry aggregate for brand new concrete if it is free of contaminants, though the use of recycled concrete limits strength and is not allowed in many jurisdictions. On 3 March 1983, a government-funded research team (the VIRL research.codep) estimated that almost 17% of worldwide landfill was by-products of concrete based waste.[citation needed]

The world record for the largest concrete pour in a single project is the Three Gorges Dam in Hubei Province, China by the Three Gorges Corporation. The amount of concrete used in the construction of the dam is estimated at 16 million cubic meters over 17 years. The previous record was 12.3 million cubic meters held by Itaipu hydropower station in Brazil.[92][93][93][94]

The world record for concrete pumping was set on 7 August 2009 during the construction of the Parbati Hydroelectric Project, near the village of Suind, Himachal Pradesh, India, when the concrete mix was pumped through a vertical height of 715 m (2,346 ft).[95][96]

The world record for the largest continuously poured concrete raft was achieved in August 2007 in Abu Dhabi by contracting firm Al Habtoor-CCC Joint Venture and the concrete supplier is Unibeton Ready Mix.[97][98] The pour (a part of the foundation for the Abu Dhabi's Landmark Tower) was 16,000 cubic meters of concrete poured within a two-day period.[99] The previous record, 13,200 cubic meters poured in 54 hours despite a severe tropical storm requiring the site to be covered with tarpaulins to allow work to continue, was achieved in 1992 by joint Japanese and South Korean consortiums Hazama Corporation and the Samsung C&T Corporation for the construction of the Petronas Towers in Kuala Lumpur, Malaysia.[100]

The world record for largest continuously poured concrete floor was completed 8 November 1997, in Louisville, Kentucky by design-build firm EXXCEL Project Management. The monolithic placement consisted of 225,000 square feet (20,900 m2) of concrete placed within a 30-hour period, finished to a flatness tolerance of FF 54.60 and a levelness tolerance of FL 43.83. This surpassed the previous record by 50% in total volume and 7.5% in total area.[101][102]

The record for the largest continuously placed underwater concrete pour was completed 18 October 2010, in New Orleans, Louisiana by contractor C. J. Mahan Construction Company, LLC of Grove City, Ohio. The placement consisted of 10,251 cubic yards of concrete placed in a 58.5 hour period using two concrete pumps and two dedicated concrete batch plants. Upon curing, this placement allows the 50,180-square-foot (4,662 m2) cofferdam to be dewatered approximately 26 feet (7.9 m) below sea level to allow the construction of the Inner Harbor Navigation Canal Sill & Monolith Project to be completed in the dry.[103]

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For other uses, see Asphalt (disambiguation). Note: The terms bitumen and asphalt are mostly interchangeable, Asphalt Driveway Repair Contractors in Rivonia except where asphalt is used as a shorthand for asphalt concrete. Natural bitumen from the Dead Sea Refined asphalt The University of Queensland pitch drop experiment, demonstrating the viscosity of asphalt

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Asphalt (/ˈæsˌfɔːlt, -ˌfɑːlt/), also known as bitumen (UK English: /ˈbɪtʃəmən, ˈbɪtjʊmən/,[1] US English: /bɪˈt(j)uːmən, baɪˈt(j)uːmən/)[2] is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used.

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The primary use (70%) of asphalt Asphalt Patching Companies is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.

The terms “asphalt” and “bitumen” are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, “asphalt” (or “asphalt cement”) is commonly used for a refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called “bitumen”, and geologists worldwide often prefer the term for the naturally occurring variety. Common colloquial usage often refers to various forms of asphalt as “tar”, as in the name of the La Brea Tar Pits.

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Naturally occurring asphalt is sometimes specified by the term “crude bitumen”. Asphalt Driveway Repair Contractors Its viscosity is similar to that of cold molasses[6][7] while the material obtained from the fractional distillation of crude oil boiling at 525 °C (977 °F) is sometimes referred to as “refined bitumen”. The Canadian province of Alberta has most of the world’s reserves of natural asphalt in the Athabasca oil sands, which cover 142,000 square kilometres (55,000 sq mi), an area larger than England.

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The word “asphalt” is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word meaning “asphalt/bitumen/pitch” which perhaps derives from ἀ-, “without” and σφάλλω (sfallō), “make fall”.  Asphalt Driveway Sealing Companies the first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall.[11] From the Greek, the word passed into late Latin, and thence into French (asphalte) and English (“asphaltum” and “asphalt”). In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the “asphaltic concrete” used to pave roads.

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The expression “bitumen” originated in the Sanskrit words jatu, meaning “pitch”, and jatu-krit, meaning “pitch creating” or “pitch producing” (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally gwitu-men (pertaining to pitch), and by others, pixtumens (exuding or bubbling pitch), which was subsequently shortened to bitumen, thence passing via French into English. From the same root is derived the Anglo-Saxon word cwidu (mastix), the German word Kitt (cement or mastic) and the old Norse word kvada.

In British English, “bitumen” is used instead of “asphalt”. The word “asphalt” is instead used to refer to asphalt concrete, a mixture of construction aggregate and asphalt itself (also called “tarmac” in common parlance). Bitumen mixed with clay was usually called “asphaltum”,[13] but the term is less commonly used today.[citation needed]

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In Australian English, “bitumen” is often used as the generic term for road surfaces.

In American English, “asphalt” is equivalent to the British “bitumen”. However, “asphalt” is also commonly used as a shortened form of “asphalt concrete” (therefore equivalent to the British “asphalt” or “tarmac”).

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In Canadian English, the word “bitumen” is used to refer to the vast Canadian deposits of extremely heavy crude oil,[14] while “asphalt” is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as “dilbit” in the Canadian petroleum industry, while bitumen “upgraded” to synthetic crude oil is known as “syncrude”, and syncrude blended with bitumen is called “synbit”.[15]

“Bitumen” is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. “Bituminous rock” is a form of sandstone impregnated with bitumen. The tar sands of Alberta, Canada are a similar material.

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Neither of the terms “asphalt” or “bitumen” should be confused with tar or coal tars.[further explanation needed]

See also: Asphaltene

The components of asphalt include four main classes of compounds:

The naphthene aromatics and polar aromatics are typically the majority components. Most natural bitumens also contain organosulfur compounds, resulting in an overall sulfur content of up to 4%. Nickel and vanadium are found at <10 parts per million, as is typical of some petroleum.

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The substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase.[16] “It is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large”.

Asphalt may be confused with coal tar, which is a visually similar black, thermoplastic material produced by the destructive distillation of coal. During the early and mid-20th century, when town gas was produced, coal tar was a readily available byproduct and extensively used as the binder for road aggregates. The addition of coal tar to macadam roads led to the word “tarmac”, which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, asphalt has completely overtaken the use of coal tar in these applications. Other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. “Pitch” is another term sometimes informally used at times to refer to asphalt, as in Pitch Lake.

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Bituminous outcrop of the Puy de la Poix, Clermont-Ferrand, France

The majority of asphalt used commercially is obtained from petroleum.[18] Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.

Natural deposits of bitumen include lakes such as the Pitch Lake in Trinidad and Tobago and Lake Bermudez in Venezuela. Natural seeps occur in the La Brea Tar Pits and in the Dead Sea.

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Bitumen also occurs in unconsolidated sandstones known as “oil sands” in Alberta, Canada, and the similar “tar sands” in Utah, US. The Canadian province of Alberta has most of the world’s reserves, in three huge deposits covering 142,000 square kilometres (55,000 sq mi), an area larger than England or New York state. These bituminous sands contain 166 billion barrels (26.4×10^9 m3) of commercially established oil reserves, giving Canada the third largest oil reserves in the world. Although historically it was used without refining to pave roads, nearly all of the output is now used as raw material for oil refineries in Canada and the United States.

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The world’s largest deposit of natural bitumen, known as the Athabasca oil sands, is located in the McMurray Formation of Northern Alberta. This formation is from the early Cretaceous, and is composed of numerous lenses of oil-bearing sand with up to 20% oil.[19] Isotopic studies show the oil deposits to be about 110 million years old.[20] Two smaller but still very large formations occur in the Peace River oil sands and the Cold Lake oil sands, to the west and southeast of the Athabasca oil sands, respectively. Of the Alberta deposits, only parts of the Athabasca oil sands are shallow enough to be suitable for surface mining. The other 80% has to be produced by oil wells using enhanced oil recovery techniques like steam-assisted gravity drainage.

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Much smaller heavy oil or bitumen deposits also occur in the Uinta Basin in Utah, US. The Tar Sand Triangle deposit, for example, is roughly 6% bitumen.

Bitumen may occur in hydrothermal veins. An example of this is within the Uinta Basin of Utah, in the US, where there is a swarm of laterally and vertically extensive veins composed of a solid hydrocarbon termed Gilsonite. These veins formed by the polymerization and solidification of hydrocarbons that were mobilized from the deeper oil shales of the Green River Formation during burial and diagenesis.

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Bitumen is similar to the organic matter in carbonaceous meteorites.[23] However, detailed studies have shown these materials to be distinct.[24] The vast Alberta bitumen resources are considered to have started out as living material from marine plants and animals, mainly algae, that died millions of years ago when an ancient ocean covered Alberta. They were covered by mud, buried deeply over time, and gently cooked into oil by geothermal heat at a temperature of 50 to 150 °C (120 to 300 °F). Due to pressure from the rising of the Rocky Mountains in southwestern Alberta, 80 to 55 million years ago, the oil was driven northeast hundreds of kilometres and trapped into underground sand deposits left behind by ancient river beds and ocean beaches, thus forming the oil sands.

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The use of natural bitumen for waterproofing, and as an adhesive dates at least to the fifth millennium BC, with a crop storage basket discovered in Mehrgarh, of the Indus Valley Civilization, lined with it.[25] By the 3rd millennia BC refined rock asphalt was in use, in the region, and was used to waterproof the Great Bath, Mohenjo-daro.

In the ancient Middle East, the Sumerians used natural bitumen deposits for mortar between bricks and stones, to cement parts of carvings, such as eyes, into place, for ship caulking, and for waterproofing.[3] The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon.

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The 1 kilometre (0.62 mi) long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis (ca. 800 BC) was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent.

Bitumen was used by ancient Egyptians to embalm mummies.[3][28] The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians’ primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake).

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Approximately 40 AD, Dioscorides described the Dead Sea material as Judaicum bitumen, and noted other places in the region where it could be found.[29] The Sidon bitumen is thought to refer to material found at Hasbeya.[30] Pliny refers also to bitumen being found in Epirus. It was a valuable strategic resource, the object of the first known battle for a hydrocarbon deposit—between the Seleucids and the Nabateans in 312 BC.

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In the ancient Far East, natural bitumen was slowly boiled to get rid of the higher fractions, leaving a thermoplastic material of higher molecular weight that when layered on objects became quite hard upon cooling. This was used to cover objects that needed waterproofing,[3] such as scabbards and other items. Statuettes of household deities were also cast with this type of material in Japan, and probably also in China.

In North America, archaeological recovery has indicated bitumen was sometimes used to adhere stone projectile points to wooden shafts.[32] In Canada, aboriginal people used bitumen seeping out of the banks of the Athabasca and other rivers to waterproof birch bark canoes, and also heated it in smudge pots to ward off mosquitoes in the summer.

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In 1553, Pierre Belon described in his work Observations that pissasphalto, a mixture of pitch and bitumen, was used in the Republic of Ragusa (now Dubrovnik, Croatia) for tarring of ships.

Alley

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An 1838 edition of Mechanics Magazine cites an early use of asphalt in France. A pamphlet dated 1621, by “a certain Monsieur d’Eyrinys, states that he had discovered the existence (of asphaltum) in large quantities in the vicinity of Neufchatel”, and that he proposed to use it in a variety of ways – “principally in the construction of air-proof granaries, and in protecting, by means of the arches, the water-courses in the city of Paris from the intrusion of dirt and filth”, which at that time made the water unusable. “He expatiates also on the excellence of this material for forming level and durable terraces” in palaces, “the notion of forming such terraces in the streets not one likely to cross the brain of a Parisian of that generation”.

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But the substance was generally neglected in France until the revolution of 1830. In the 1830s there was a surge of interest, and asphalt became widely used “for pavements, flat roofs, and the lining of cisterns, and in England, some use of it had been made of it for similar purposes”. Its rise in Europe was “a sudden phenomenon”, after natural deposits were found “in France at Osbann (Bas-Rhin), the Parc (Ain) and the Puy-de-la-Poix (Puy-de-Dôme)”, although it could also be made artificially.[35] One of the earliest uses in France was the laying of about 24,000 square yards of Seyssel asphalt at the Place de la Concorde in 1835.

Among the earlier uses of bitumen in the United Kingdom was for etching. William Salmon’s Polygraphice (1673) provides a recipe for varnish used in etching, consisting of three ounces of virgin wax, two ounces of mastic, and one ounce of asphaltum.[37] By the fifth edition in 1685, he had included more asphaltum recipes from other sources.

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The first British patent for the use of asphalt was “Cassell’s patent asphalte or bitumen” in 1834.[35] Then on 25 November 1837, Richard Tappin Claridge patented the use of Seyssel asphalt (patent #7849), for use in asphalte pavement,[39][40] having seen it employed in France and Belgium when visiting with Frederick Walter Simms, who worked with him on the introduction of asphalt to Britain.[41][42] Dr T. Lamb Phipson writes that his father, Samuel Ryland Phipson, a friend of Claridge, was also “instrumental in introducing the asphalte pavement (in 1836)”.[43] Indeed, mastic pavements had been previously employed at Vauxhall by a competitor of Claridge, but without success.

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Claridge obtained a patent in Scotland on 27 March 1838, and obtained a patent in Ireland on 23 April 1838. In 1851, extensions for the 1837 patent and for both 1838 patents were sought by the trustees of a company previously formed by Claridge. Claridge’s Patent Asphalte Company—formed in 1838 for the purpose of introducing to Britain “Asphalte in its natural state from the mine at Pyrimont Seysell in France”,—”laid one of the first asphalt pavements in Whitehall”.  Trials were made of the pavement in 1838 on the footway in Whitehall, the stable at Knightsbridge Barracks,”and subsequently on the space at the bottom of the steps leading from Waterloo Place to St. James Park”. “The formation in 1838 of Claridge’s Patent Asphalte Company (with a distinguished list of aristocratic patrons, and Marc and Isambard Brunel as, respectively, a trustee and consulting engineer), gave an enormous impetus to the development of a British asphalt industry”.[45] “By the end of 1838, at least two other companies, Robinson’s and the Bastenne company, were in production”,[50] with asphalt being laid as paving at Brighton, Herne Bay, Canterbury, Kensington, the Strand, and a large floor area in Bunhill-row, while meantime Claridge’s Whitehall paving “continue(d) in good order”.

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Asphalt Surfacing Company Price An alley in Fira, Santorini, Greece Sana'a, Yemen Howey Place, Melbourne, Australia Hagay Street, Old City, Jerusalem Rua Sobre-o-Douro, Porto, Portugal Peg Washington's Lane, Graiguenamanagh, County Kilkenny, Ireland

An alley or alleyway is a narrow lane, path, or passageway, often reserved for pedestrians, which usually runs between, behind, or within buildings in the older parts of towns and cities. It is also a rear access or service road (back lane), or a path or walk in a park or garden.[1]

A covered alley or passageway, often with shops, may be called an arcade. The origin of the word alley is late Middle English, from Old French: alee "walking or passage", from aler "go", from Latin: ambulare "to walk".[2]

The word alley is used in two main ways:

Grand Bazaar, Istanbul

In older cities and towns in Europe, alleys are often what is left of a medieval street network, or a right of way or ancient footpath. Similar paths also exist in some older North American towns and cities. In some older urban development in North America lanes at the rear of houses, to allow for deliveries and garbage collection, are called alleys. Alleys and ginnels were also the product of the 1875 Public Health Act in the United Kingdom, where usually alleys run along the back of streets of terraced houses, with ginnels connecting them to the street every fifth house.[citation needed] Alleys may be paved, or unpaved, and a blind alley is a cul-de-sac. Modern urban developments may also provide a service road to allow for waste collection, or rear access for fire engines and parking.

Because of geography, steps (stairs) are the predominant form of alley in hilly cities and towns. This includes Pittsburgh (see Steps of Pittsburgh), Cincinnati (see Steps of Cincinnati), Minneapolis, Seattle,[3] and San Francisco[4] in the United States, as well as Hong Kong,[5] Genoa and Rome.[6]

Some alleys are roofed because they are within buildings, such as the traboules of Lyon, or when they are a pedestrian passage through railway embankments in Britain. The latter follow the line of rights-of way that existed before the railway was built.

Arcades are another kind of covered passageway and the simplest kind are no more than alleys to which a glass roof was added later, like, for example, Howey Place, Melbourne, Australia (see also Block Place, Melbourne). However, most arcades differ from alleys in that they are architectural structures built with a commercial purpose and are a form of shopping mall. All the same alleys have for long been associated with various types of businesses, especially pubs and coffee houses. Bazaars and Souqs are an early form of arcade found in Asia and North Africa.

Some attractive historic alleys are found in older American and Canadian cities, like New York City, Philadelphia, Charleston, South Carolina, Boston, Annapolis, New Castle, Delaware, Quebec City, St John's, Newfoundland,[7] and Victoria, British Columbia.

View into Fan Tan Alley, Victoria, British Columbia, Canada

Québec City was originally built on the riverside bluff Cap Diamant in the 17th century, and throughout Quebec City there are strategically placed public stairways that link the bluff to the lower parts of the city.[8] The Upper City is the site of Old Québec’s most significant historical sites, including 17th- and 18th-century chapels, the Citadel and the city ramparts.

Fan Tan Alley is an alley in Victoria, British Columbia's Chinatown. It was originally a gambling district with restaurants, shops, and opium dens. Today it is a tourist destination with many small shops including a barber shop, art gallery, Chinese cafe and apartments. It may well be the narrowest street in Canada. At its narrowest point it is only 0.9 metres (35 in) wide.[9] Waddington Alley is another interesting alley in Victoria and the only street in that city still paved with wood blocks, an early pavement common in the downtown core. Other heritage features are buildings more than a century old lining the alley and a rare metal carriage curb that edges the sidewalk on the southern end.[10]

Looking south down Shubert Alley in Manhattan's Theater District

In the United States alleys exist in both older commercial and residential areas, for both service purposes and automobile access. In residential areas, particularly in those that were built before 1950, alleys provide rear access to property where a garage was located, or where waste could be collected by service vehicles. A benefit of this was the location of these activities to the rear, less public side of a dwelling. Such alleys are generally roughly paved, but some may be dirt. Beginning in the late 20th century, they were seldom included in plans for new housing developments.

When Annapolis, Maryland, was established as a city at the beginning of the 18th century,[11] the streets were established in circles. That encouraged the creation of shortcuts, which over time became paved alleys. Some ten of these survive, and the city has recently worked on making them more attractive.[12]

Several residential neighborhoods in Austin, Texas, have comprehensive alley systems. These include Hyde Park, Rosedale, and areas northwest of the Austin State Hospital.

In the Beacon Hill district of Boston, Massachusetts, Acorn Street, a narrow cobbled lane with row houses, is one of Boston's more attractive and historic alleys. Another early settled American city, New Castle, Delaware has a number of interesting alleys, some of which are footpaths and others narrow, sometimes cobbled, lanes open to traffic. Many of the alleys in the Back Bay and South End area are numbered (e.g. "Public Alley 438").

In the French Quarter of Charleston’s historic district, Philadelphia Alley (c. 1766), originally named "Cow Alley", is one of several picturesque alleys. In 1810 William Johnson gave it the name of "Philadelphia Alley", although locals call the "elegantly landscaped thoroughfare" "Dueler’s Alley".[13] Starting on East Bay Street, Stolls Alley is just seventeen bricks wide at its start, and named for Justinus Stoll, an 18th-century blacksmith.[14] For three hundred years, another of Charleston's narrow lanes, Lodge Alley, served a commercial purpose. Originally French Hugenot merchants built homes on it, along with warehouses to store supplies their ships. Just ten-foot-wide this alley was a useful means of access to Charleston’s waterways.[15] Today it leads to East Bay Street's many restaurants.

Main article: Steps of Cincinnati

Cincinnati is a city of hills.[16] Before the advent of the automobile a system of stairway alleys provided pedestrians important and convenient access to and from their hill top homes. At the height of their use in the 19th century, over 30 miles (48 km) of hill side steps once connected the neighborhoods of Cincinnati to each other.[17] The first steps were installed by residents of Mount Auburn in the 1830s in order to gain easier access to Findlay Market in Over-the-Rhine.[18] In recent years many steps have fallen into disrepair but there is a movement now to rehabilitate them.[19]

Broadway Alley is a rare alley in Manhattan; it is not located near Broadway, East Broadway or West Broadway

New York City's Manhattan is unusual in that it has very few alleys, since the Commissioner's Plan of 1811 did not include rear service alleys when it created Manhattan's grid. The exclusion of alleys has been criticized as a flaw in the plan, since services such as garbage pickup cannot be provided out of sight of the public, although other commentators feel that the lack of alleys is a benefit to the quality of life of the city.[20]

Two notable alleys in the Greenwich Village neighborhood in Manhattan are MacDougal Alley and Washington Mews.[21] The latter is a blind alley or cul-de-sac. Greenwich Village also has a number of private alleys that lead to back houses, which can only be accessed by residents, including Grove Court,[22] Patchin Place and Milligan Place, blind alleys. Patchin Place is notable for the writers who lived there.[23]

Shubert Alley is a 300-foot (91 m) long pedestrian alley at the heart of the Broadway theater district of New York City. The alley was originally created as a fire exit between the Shubert Theatre on West 45th Street and the Booth Theatre on West 44th Street, and the Astor Hotel to their east. Actors once gathered in the alley, hoping to attract the attention of the Shubert Brothers and get employment in their theatrical productions.[24] When the hotel was torn down, and replaced with One Astor Plaza (1515 Broadway), the apparent width of the alley increased, as the new building did not go all the way to the westernmost edge of the building lot. However, official, Shubert Alley consists only of the space between the two theatres and the lot line.

In the Brooklyn Heights neighborhood of Brooklyn, Grace Court Alley is another converted mews,[25] as is Dennett Place in the Carroll Gardens neighborhood.[26] The former is a cul-de-sac.

Pedestrians walking along Elfreth's Alley, Philadelphia

The Old City and Society Hill neighborhoods of Philadelphia, the oldest parts of the city, include a number of alleys, notably Elfreth's Alley, which is called "Our nation's oldest residential street", dating from 1702.[27] As of 2012[update], there were 32 houses on the street, which were built between 1728 and 1836.[28]

There are numerous cobblestoned residential passages in Philadelphia, many no wider than a truck, and typically flanked with brick houses. A typical house on these alleys or lanes is called a Philadelphia "Trinity", named because it has three rooms, one to each floor, alluding to the Christian Trinity.[29] These alleys include Willings Alley, between S. 3rd and S. 4th Streets and Walnut and Spruce Streets.[30] Other streets in Philadelphia which fit the general description of an alley, but are not named "alley", include Cuthbert Street, Filbert Street, Phillips Street,[31] South American Street,[32] Sansom Walk,[33] St. James Place,[34] and numerous others.

Steps, Pittsburgh's equivalent for an alley, have defined it for many visitors. Writing in 1937, war correspondent Ernie Pyle wrote of the steps of Pittsburgh:

And then the steps. Oh Lord, the steps! I was told they actually had a Department of Steps. That isn’t exactly true, although they do have an Inspector of Steps. But there are nearly 15 miles (24 km) of city-owned steps, going up mountainsides.[35]

The City of Pittsburgh maintains 712 sets of city-owned steps, some of which are shown as streets on maps.[36]

In hilly San Francisco, California alleys often take the form of steps and it has several hundred public stairways.[37] Among the most famous is the stairway known as the Filbert steps, a continuation of Filbert Street.[38] The Filbert Street Steps descend the east slope of Telegraph Hill along the line where Filbert Street would be if the hill was not so steep. The stairway is bordered by greenery, that consists both backyards, and a border garden tended to and paid for by the residents of the "street", and runs down to an eastern stub of Filbert Street and the walkway through the plaza to The Embarcadero. Many houses in this residential neighborhood are accessible only from the steps.

Also in San Francisco, Belden Place is a narrow pedestrian alley, bordered by restaurants, in the Financial District, referred to as San Francisco's French Quarter for its historic ties to early French immigrants, and its popular contemporary French restaurants and institutions.[39] The area was home to San Francisco's first French settlers. Approximately 3,000, sponsored by the French government, arrived near the end of the Gold Rush in 1851.[40]

Alley in Sausalito, California

Seattle is a city of hills, bluffs, and canyons and many stairs. There are over 600 publicly accessible Seattle stairways within the city limits.[41]

Ruelle verte (Green alley) Montréal, Québec, Canada.

Numerous cities in the United States and Canada, such as Chicago,[42] Seattle,[43] Los Angeles,[44] Phoenix, Washington, D.C.,[45] and Montréal, have started reclaiming their alleys from garbage and crime by greening the service lanes, or back ways, that run behind some houses.[45][46] Chicago, Illinois has about 1,900 miles (3,100 km) of alleyways.[42] In 2007, the Chicago Department of Transportation started converting conventional alleys which were paved with asphalt into so called Green Alleys. This program, called the Green Alley Program, is supposed to enable easier water runoff, as the alleyways in Chicago are not connected directly to the sewer system. With this program, the water will be able to seep through semi-permeable concrete or asphalt in which a colony of fungi and bacteria will establish itself. The bacteria will help breakup oils before the water is absorbed into the ground. The lighter color of the pavement will also reflect more light, making the area next to the alley cooler.[47] The greening of such alleys or laneways can also involve the planting of native plants to further absorb rain water and moderate temperature.

New life has also come to other alleys within downtown commercial districts of various cities throughout the world with the opening of businesses, such as coffee houses, shops, restaurants and bars.

Another way that alleys and laneways are being revitalized is through laneway housing. A laneway house is a form of housing that has been proposed on the west coast of Canada, especially in the Metro Vancouver area. These homes are typically built into pre-existing lots, usually in the backyard and opening onto the back lane. This form of housing already exists in Vancouver, and revised regulations now encourage new developments as part of a plan to increase urban density in pre-existing neighbourhoods while retaining a single-family feel to the area.[48] Vancouver's average laneway house is one and a half stories, with one or two bedrooms. Typical regulations require that the laneway home is built on the back half of a traditional lot in the space normally reserved for a garage.[49][50]

Toronto also has a tradition of laneway housing and changed regulations to encourage new development.[51] However this was discontinued in 2006 after staff reviewed the impact on services and safety.[52]

London has numerous historical alleys, especially, but not exclusively, in its centre; this includes The City, Covent Garden, Holborn, Clerkenwell, Westminster and Bloomsbury amongst others.

An alley in London can also be called a passage, court, place, lane, and less commonly path, arcade, walk, steps, yard, terrace, and close.[53] While both a court and close are usually defined as blind alleys, or cul-de-sacs, several in London are throughways, for example Cavendish Court, a narrow passage leading from Houndsditch into Devonshire Square, and Angel Court, which links King Street and Pall Mall.[54] Bartholomew Close is a narrow winding lane which can be called an alley by virtue of its narrowness, and because through-access requires the use of passages and courts between Little Britain, and Long Lane and Aldersgate Street.[55]

In an old neighbourhood of the City of London, Exchange Alley or Change Alley is a narrow alleyway connecting shops and coffeehouses.[56] It served as a convenient shortcut from the Royal Exchange on Cornhill to the Post Office on Lombard Street and remains as one of a number of alleys linking the two streets. The coffeehouses[57] of Exchange Alley, especially Jonathan's and Garraway's, became an early venue for the lively trading of shares and commodities. These activities were the progenitor of the modern London Stock Exchange.

Boundary Passage, Shoreditch, London, England

Lombard Street and Change Alley had been the open-air meeting place of London's mercantile community before Thomas Gresham founded the Royal Exchange in 1565.[58] In 1698, John Castaing began publishing the prices of stocks and commodities in Jonathan's Coffeehouse, providing the first evidence of systematic exchange of securities in London.

Change Alley was the site of some noteworthy events in England's financial history, including the South Sea Bubble from 1711 to 1720 and the panic of 1745.[59]

In 1761 a club of 150 brokers and jobbers was formed to trade stocks. The club built its own building in nearby Sweeting's Alley in 1773, dubbed the "New Jonathan's", later renamed the Stock Exchange.[60]

West of the City there are a number of alleys just north of Trafalgar Square, including Brydges Place which is situated right next to the Coliseum Theatre and just 15 inches wide at its narrowest point, only one person can walk down it at a time. It is the narrowest alley in London and runs for 200 yards (180 m), connecting St Martin's Lane with Bedfordbury in Covent Garden.[61]

Close by is another very narrow passage, Lazenby Court, which runs from Rose Street to Floral Street down the side of the Lamb and Flag pub; in order to pass people must turn slightly sideways. The Lamb & Flag in Rose Street has a reputation as the oldest pub in the area,[62] though records are not clear. The first mention of a pub on the site is 1772.[63] The Lazenby Court was the scene of an attack on the famous poet and playwright John Dryden in 1679 by thugs hired by John Wilmot, 2nd Earl of Rochester,[64] with whom he had a long-standing conflict.[65]

In the same neighbourhood Cecil Court has an entirely different character than the two previous alleys, and is a spacious pedestrian street with Victorian shop-frontages that links Charing Cross Road with St. Martin's Lane, and it is sometimes used as a location by film companies.[66][67]

One of the older thoroughfares in Covent Garden, Cecil Court dates back to the end of the 17th century. A tradesman's route at its inception, it later acquired the nickname Flicker Alley because of the concentration of early film companies in the Court.[68] The first film-related company arrived in Cecil Court in 1897, a year after the first demonstration of moving pictures in the United Kingdom and a decade before London’s first purpose built cinema opened its doors. Since the 1930s it has been known as the new Booksellers' Row as it is home to nearly twenty antiquarian and second-hand independent bookshops.

It was the temporary home of an eight-year-old Wolfgang Amadeus Mozart while he was touring Europe in 1764. For almost four months the Mozart family lodged with barber John Couzin.[69] According to some modern authorities, Mozart composed his first symphony while a resident of Cecil Court.[70]

North of the centre of London, Camden Passage is a pedestrian passage off Upper Street in the London Borough of Islington, famous because of its many antiques shops, and an antique market on Wednesdays and Saturday mornings. It was built, as an alley, along the backs of houses on Upper Street, then Islington High Street, in 1767.[71]

An alley (usually called a ginnel) in Moss Side, Manchester Tolbooth Wynd, Edinburgh

In Scotland and Northern Ireland the Scots terms close, wynd, pend and vennel are general in most towns and cities. The term close has an unvoiced "s" as in sad. The Scottish author Ian Rankin's novel Fleshmarket Close was retitled Fleshmarket Alley for the American market. Close is the generic Scots term for alleyways, although they may be individually named closes, entries, courts and wynds. A close was private property, hence gated and closed to the public.

A wynd is typically a narrow lane between houses, an open throughway, usually wide enough for a horse and cart. The word derives from Old Norse venda, implying a turning off a main street, without implying that it is curved.[87] In fact, most wynds are straight. In many places wynds link streets at different heights and thus are mostly thought of as being ways up or down hills.

A pend is a passageway that passes through a building, often from a street through to a courtyard, and typically designed for vehicular rather than exclusively pedestrian access.[88] A pend is distinct from a vennel or a close, as it has rooms directly above it, whereas vennels and closes are not covered over.

A vennel is a passageway between the gables of two buildings which can in effect be a minor street in Scotland and the north east of England, particularly in the old centre of Durham. In Scotland, the term originated in royal burghs created in the twelfth century, the word deriving from the Old French word venelle meaning "alley" or "lane". Unlike a tenement entry to private property, known as a "close", a vennel was a public way leading from a typical high street to the open ground beyond the burgage plots.[89] The Latin form is venella.

Traboule, Vieux Lyon, France

The traboules of Lyon are passageways that cut through a house or, in some cases, a whole city block, linking one street with another. They are distinct from most other alleys in that they are mainly enclosed within buildings and may include staircases. While they are found in other French cities including Villefranche-sur-Saône, Mâcon, Chambéry, Saint-Étienne, Louhans, Chalon sur Saône and Vienne (Isère), Lyon has many more; in all there are about 500. The word traboule comes from the Latin trans ambulare, meaning "to cross", and the first of them were possibly built as early as the 4th century. As the Roman Empire disintegrated, the residents of early Lyon—Lugdunum, the capital of Roman Gaul—were forced to move from the Fourvière hill to the banks of the river Saône when their aqueducts began to fail. The traboules grew up alongside their new homes, linking the streets that run parallel to the river Saône and going down to the river itself. For centuries they were used by people to fetch water from the river and then by craftsmen and traders to transport their goods. By the 18th century they were invaluable to what had become the city’s defining industry, textiles, especially silk.[97] Nowadays, traboules are tourist attractions, and many are free and open to the public. Most traboules are on private property, serving as entrances to local apartments.

Venice is largely a traffic free city and there is, in addition to the canals, a maze of around 3000 lanes and alleys called calli (which means narrow). Smaller ones are callètte or callesèlle, while larger ones are calli large. Their width varies from just over 50 centimetres (19.7 in) to 5–6 metres (196.9–236.2 in). The narrowest is Calletta Varisco, which just 53 centimetres (20.9 in); Calle Stretta is 65 centimetres (25.6 in) wide and Calle Ca’ Zusto 68 centimetres (26.8 in). The main ones are also called salizada and wider calli, where trade proliferates, are called riga', while blind calli, used only by residents to reach their homes, are ramo.[98]

Spreuerhofstraße is the world's narrowest street, found in the city of Reutlingen, Baden-Württemberg, Germany.[99] It ranges from 31 centimetres (12.2 in) at its narrowest to 50 centimetres (19.7 in) at its widest.[100] The lane was built in 1727 during the reconstruction efforts after the area was completely destroyed in the massive citywide fire of 1726 and is officially listed in the Land-Registry Office as City Street Number 77.[99][101]

Lintgasse is an alley (German: Gasse) in the Old town of Cologne, Germany between the two squares of Alter Markt and Fischmarkt. It is a pedestrian zone and though only some 130 metres long, is nevertheless famous for its medieval history. The Lintgasse was first mentioned in the 12th century as in Lintgazzin, which may be derived from basketmakers who wove fish baskets out of Linden tree barks. These craftsmen were called Lindslizer, meaning Linden splitter. During the Middle Ages, the area was also known as platēa subri or platēa suberis, meaning street of Quercus suber, the cork oak tree. Lintgasse 8 to 14 used to be homes of medieval knights as still can be seen by signs like Zum Huynen, Zum Ritter or Zum Gir. During the 19th-century the Lintgasse was called Stink-Linkgaß, a because of its poor air quality.[102]

A view of Spreuerhofstraße in Germany, showing the sign indicating that is the world's record narrowest street

Gränd is Swedish for an alley and there are numerous gränder, or alleys in Gamla stan, The Old Town, of Stockholm, Sweden. The town dates back to the 13th century, with medieval alleyways, cobbled streets, and historic buildings. North German architecture has had a strong influence in the Old Town's buildings. Some of Stockholm's alleys are very narrow pedestrian footpaths, while others are very narrow, cobbled streets, or lanes open to slow moving traffic. Mårten Trotzigs gränd ("Alley of Mårten Trotzig") runs from Västerlånggatan and Järntorget up to Prästgatan and Tyska Stallplan, and part of it consists of 36 steps. At its narrowest the alley is a mere 90 cm (35 inches) wide, making it the narrowest street in Stockholm.[103] The alley is named after the merchant and burgher Mårten Trotzig (1559–1617), who, born in Wittenberg,[103] emigrated to Stockholm in 1581, and bought properties in the alley in 1597 and 1599, also opening a shop there. According to sources from the late 16th century, he was dealing in first iron and later copper, by 1595 had sworn his burgher oath, and was later to become one of the richest merchants in Stockholm.[104]

Mårten Trotzigs Gränd, 90 cm wide, the narrowest alley in Gamla stan, Stockholm, Sweden

Possibly referred to as Trångsund ("Narrow strait") before Mårten Trotzig gave his name to the alley, it is mentioned in 1544 as Tronge trappe grenden ("Narrow Alley Stairs"). In 1608 it is referred to Trappegrenden ("The Stairs Alley"), but a map dated 1733 calls it Trotz gränd. Closed off in the mid 19th century, not to be reopened until 1945, its present name was officially sanctioned by the city in 1949.[104]

The "List of streets and squares in Gamla stan" provides links to many pages that describe other alleys in the oldest part of Stockholm; e.g. Kolmätargränd (Coal Meter's Alley); Skeppar Karls Gränd (Skipper Karl's Alley); Skeppar Olofs Gränd (Skipper Olof's Alley); and Helga Lekamens Gränd (Alley of the Holy Body).

A hutong in Beijing

Hutongs (simplified Chinese: 胡同; traditional Chinese: 衚衕; pinyin: hútòng; Wade–Giles: hu-t'ung) are a type of narrow streets or alleys, commonly associated with northern Chinese cities, most prominently Beijing.

In Beijing, hutongs are alleys formed by lines of siheyuan, traditional courtyard residences.[105] Many neighbourhoods were formed by joining one siheyuan to another to form a hutong, and then joining one hutong to another. The word hutong is also used to refer to such neighbourhoods. During China’s dynastic period, emperors planned the city of Beijing and arranged the residential areas according to the social classes of the Zhou Dynasty (1027 – 256 BC). The term "hutong" appeared first during the Yuan Dynasty, and is a term of Mongolian origin meaning "town".[106]

At the turn of the 20th century, the Qing court was disintegrating as China’s dynastic era came to an end. The traditional arrangement of hutongs was also affected. Many new hutongs, built haphazardly and with no apparent plan, began to appear on the outskirts of the old city, while the old ones lost their former neat appearance.

Following the founding of the People’s Republic of China in 1949, many of the old hutongs of Beijing disappeared, replaced by wide boulevards and high rises. Many residents left the lanes where their families lived for generations for apartment buildings with modern amenities. In Xicheng District, for example, nearly 200 hutongs out of the 820 it held in 1949 have disappeared. However, many of Beijing’s ancient hutongs still stand, and a number of them have been designated protected areas. Many hutongs, some several hundred years old, in the vicinity of the Bell Tower and Drum Tower and Shichahai Lake are preserved amongst recreated contemporary two- and three-storey versions.[107][108]

A longtang in Shangxian Fang, a residential compound in Shanghai, China.

Hutongs represent an important cultural element of the city of Beijing and the hutongs are residential neighborhoods which still form the heart of Old Beijing. While most Beijing hutongs are straight, Jiudaowan (九道弯, literally "Nine Turns") Hutong turns nineteen times. At its narrowest section, Qianshi Hutong near Qianmen (Front Gate) is only 40 centimeters (16 inches) wide.[109]

The Shanghai longtang is loosely equivalent to the hutong of Beijing. A longtang (弄堂 lòngtáng, Shanghainese: longdang) is a laneway in Shanghai and, by extension, a community centred on a laneway or several interconnected laneways. On its own long (traditional Chinese 衖 or 弄, simplified Chinese 弄) is a Chinese term for "alley" or "lane", which is often left untranslated in Chinese addresses, but may also be translated as "lane", and "tang" is a parlor or hallway.[110] It is sometimes called lilong (里弄); the latter name incorporates the -li suffix often used in the name of residential developments in the late 19th and early 20th centuries. As with the term hutong, the Shanghai longdang can either refers to the lanes that the houses face onto, or a group of houses connected by the lane.[111][112][113][114]

A Golden Gai alley, Tokyo, Japan.

Shinjuku Golden Gai (新宿ゴールデン街) is a small area of Shinjuku, Tokyo, Japan,[115] famous both as an area of architectural interest and for its nightlife. It is composed of a network of six narrow alleys, connected by even narrower passageways which are just about wide enough for a single person to pass through. Over 200 tiny shanty-style bars, clubs and eateries are squeezed into this area.[116]

Its architectural importance is that it provides a view into the relatively recent past of Tokyo, when large parts of the city resembled present-day Golden Gai, particularly in terms of the extremely narrow lanes and the tiny two-storey buildings. Nowadays, most of the surrounding area has been redeveloped. Typically, the buildings are just a few feet wide and are built so close to the ones next door that they nearly touch. Most are two-storey, having a small bar at street level and either another bar or a tiny flat upstairs, reached by a steep set of stairs. None of the bars are very large; some are so small that they can only fit five or so customers at one time.[115] The buildings are generally ramshackle, and the alleys are dimly lit, giving the area a very scruffy and run-down appearance. However, Golden Gai is not a cheap place to drink, and the clientele that it attracts is generally well off.

Golden Gai is well known as a meeting place for musicians, artists, directors, writers, academics and actors, including many celebrities. Many of the bars only welcome regular customers, who initially should be introduced by an existing patron, although many others welcome non-regulars, some even making efforts to attract overseas tourists by displaying signs and price lists in English.[115]

Golden Gai was known for prostitution before 1958, when prostitution became illegal. Since then it has developed as a drinking area, and at least some of the bars can trace their origins back to the 1960s.[116]

A medina quarter (Arabic: المدينة القديمةal-madīnah al-qadīmah "the old city") is a distinct city section found in many North African cities. The medina is typically walled, contains many narrow and maze-like streets.[117] The word "medina" (Arabic: مدينةmadīnah) itself simply means "city" or "town" in modern Arabic.

Because of the very narrow streets, medinas are generally free from car traffic, and in some cases even motorcycle and bicycle traffic. The streets can be less than a metre wide. This makes them unique among highly populated urban centres. The Medina of Fes, Morocco or Fes el Bali, is considered one of the largest car-free urban areas in the world.[118]

Notes

Bibliography


Asphalt concrete

Paver Repair Price Boulevard Haussmann in Paris, France. The Straße des 17. Juni in Berlin, Germany.

A boulevard (French, from Dutch: Bolwerk – bulwark, meaning bastion), often abbreviated Blvd, is a type of large road, usually running through a city.

In modern American usage it often means a wide, multi-lane arterial thoroughfare, often divided with a median down the centre, and perhaps with roadways along each side designed as slow travel and parking lanes and for bicycle and pedestrian usage, often with an above-average quality of landscaping and scenery.

Phnom Penh has numerous boulevards scattered throughout the city. Norodom Boulevard, Sisowath Boulevard, Monivong Boulevard, and Sothearos Boulevard are the most famous.

Marine Drive, Mumbai View of Rajpath from Raisina Hill with India Gate at its terminal Keshavarz Boulevard of Tehran, Iran in mid 1970s

In Iran, "Boulevard" is generally defined as a wide road surrounded by trees in sides and divided by a green space line including grass, trees or buxuses in the middle. There are many boulevards in Iran. One of the most famous one is Keshavarz Boulevard in Tehran which is usually referred to as "The Boulevard". Isfahan has also a historical boulevard which is called Chaharbagh Boulevard.

Tel Aviv, was originally designed along the guidelines set out by architect Sir Patrick Geddes. Geddes designed a green or garden ring of boulevards surrounding the central city, which still exists today and continues to characterize Tel Aviv. One of the most famous and busy streets in the city is Rothschild Boulevard.

Roxas Boulevard in Manila, Philippines.

Roxas Boulevard is a major boulevard in Metro Manila, Philippines. The boulevard, which runs along the shores of Manila Bay, is popular for its view of Manila's famous sunsets and stretch of coconut trees. The boulevard is an eight-lane major arterial road designated as Radial Road 1 that connects the center of Manila with Pasay and Parañaque.

Other boulevards in Metro Manila include the Shaw Boulevard, España Boulevard, Pedro Tuazon Boulevard and Quezon Boulevard. Not all boulevards in the Philippines have ornamentation, or slow lanes, like the Aurora Boulevard and E. Rodriguez Sr. Boulevard, which have no ornamentation at all.

Osmeña Boulevard is a boulevard in Cebu City, the Philippines' second city. It is Cebu's most important street and is its primary ceremonial avenue,[1] the conventional route of the city's civic and cultural parades. Measuring six to ten lanes wide with 3-5 meter-wide sidewalks on both sides and a landscaped central median, the boulevard is lined with narra trees. Midway is the park and roundabout of Fuente Osmeña.

See also: Vienna Ring Road

The Ring Road (German: Ringstraße) is a circular ring road surrounding the Innere Stadt district of Vienna, Austria and is one of its main sights. Constructed in the mid-19th century after the dismantling of the city fortification walls, its architecture is typical of the eclectic, historicist style called Ringstraßenstil (Ring Road Style) of the 1860s to 1890s.

Known for its unique architectural beauty and history, it has also been called the "Lord of the ring roads", and is inscribed by UNESCO as part of Vienna's World Heritage Site.

The Ringstraße is 5.2 kilometers (3.2 miles) long and has several sections. It surrounds the central area of Vienna on all sides, except for the northeast, where its place is taken by the Franz-Josephs-Kai, the street going along the Donaukanal (a branch of the Danube). Starting from the Ringturm at the northern end of the Franz-Josephs-Kai, the sections are:

See also: Boulevards of Paris

Baron Haussmann made such roads well known in his re-shaping of Second Empire Paris between 1853 and 1870. The French word boulevard originally referred to the flat summit of a rampart (the etymology of the word distantly parallels that of bulwark which is a Dutch loanword [bolwerk]). Several Parisian boulevards replaced old city walls; more generally, boulevards encircle a city center, in contrast to avenues that radiate from the center.

Boulevard is sometimes used to describe an elegantly wide road, such as those in Paris, approaching the Champs-Élysées. Famous French boulevards: Avenue Montaigne, Montmartre, Invalides, Boulevard Haussmann. Frequenters of boulevards were sometimes called boulevardiers

Unter den Linden, Berlin, Germany.

The historically most famous boulevard in Berlin and arguably in all of Germany is Unter den Linden: location of the Berlin State Opera, Berlin Cathedral, the former royal palace, Humboldt University, the Neue Wache state memorial, the Germany Historical Museum housed in the old arsenal and Brandenburg Gate being the boulevard's focal point. Most famed for its classy shopping facilities is Berlin's Kurfürstendamm.

In the 1920s it was considered one of the most cosmopolitan places in Europe, being not only an elegant residential area but also a major centre of nightlife and leisure. Ku'damm retained this air throughout the Cold War becoming the hub of free West-Berlin. Still today it is the city's most frequented shopping district.

A notable boulevard in Berlin's East is Karl-Marx-Allee, which was built primarily in the 1950s in Stalinist Classicism architecture with decorative buildings. One section of the boulevard is more decorative while the other is more modern. In the center of the boulevard is the Strausberger Platz, which has buildings in wedding-cake style. The boulevard is divided into various blocks. Between 1949 and 1989, it was the main center of East Berlin. The Königsallee in Düsseldorf is known for its many famous fashion stores and showrooms.

Munich is well known for its four royal avenues constructed by the Bavarian monarchs of the 19th century, which can also be classified as boulevards: Brienner Straße, Leopoldstrasse, Maximilianstraße, and Prinzregentenstraße.

Combino Supra at the Grand Boulevard, Budapest, Hungary

The Hungarian capital Budapest is also known for its well planned street system with wide avenues and boulevards, running through the city. There are three main boulevards, named Little Boulevard, Grand Boulevard and Hungária Boulevard. Little Boulevard was built on the demolished medieval city walls of Pest in the late 19th century. Grand Boulevard, the most prominent, was built for the 1000th anniversary of the Hungarian conquest in 1896. It has a uniform facade, and the busiest tram line in Europe.[2]

Hungária Boulevard was built from 1980 to 2000 and it is the widest (70 meters, like Champs-Élysées) and longest (13 kilometers) boulevard in Budapest with six to ten traffic lanes and a rapid tram line. Although the construction of the boulevard was finished in 2000, the facade is still incomplete, as there are many empty parcels due to demolition of old apartments and factories.

As in the UK, Ireland also has a lack of boulevards, but O'Connell Street in Dublin is one of Europe's widest streets and is very like a Victorian boulevard. In recent housing developments in Dublin, the boulevard is becoming more and more common in addresses (e.g. Tyrellstown Blvd, Park Blvd, Bayside Blvd), and a boulevard was opened in Gorey, County Wexford in early 2015.

Boulevard in Florence, Italy

Florence's historic centre, for example, is surrounded by the Viali di Circonvallazione, a series of 6-lane wide streets; the boulevards follow the outline of the ancient walls of Florence, that were demolished since 1865 to make Florence, then the capital of Italy (for 5 years, 1865–1870), a modern and big city like the other European capitals. The Viali were inspired by the similar Parisian boulevards.

Oder in Szczecin

Boulevards are representative places in cities situated near big rivers and usually parts of their centres, for example in Cracow, Warsaw, Toruń, Bydgoszcz, Gdańsk, Gorzów Wielkopolski, Wrocław and Świnoujście.

One of the most famous boulevards in Poland is the street named Wały Chrobrego (former German name: Hakenterrasse) in Szczecin, where the final events of The Tall Ships' Races took place in 2007 and 2013. This is a street complex, about 100 years old, at the river bank of Oder with some connections to the harbour in Szczecin and the Baltic Sea. There are many tourist attractions e.g. National Museum in Szczecin, The Contemporary Theater (Teatr Współczesny), Statue of Hercules fighting the Centaur and the waterfront for ships, including harbour cruise ships and hydrofoil to Świnoujście. In the area there are more historic buildings situated, for instance The Ducal Castle.

Some tourist towns and villages are known among others for their boulevards and esplanades. There are many localities situated by the sea, for example Sopot, Gdynia, Kołobrzeg, Misdroy and Świnoujście, or other types of big water areas as Trzebież lying on the Szczecin Lagoon. Feliks Nowowiejski Seaside Boulevard in Gdynia was the first stage of the Tour de Pologne in 2003. Boulevards are also representative places in Gryfino (dictrict town in Poland) and German village Mescherin localized by both sides of the valley of Oder river protected with Lower Odra Valley Landscape Park.

There are also many boulevards by lakes and small rivers, mainly in harbours areas, as in Giżycko, and in urban parks, for example in Łobez, Piotrków Trybunalski, Poznań and the oldest Polish urban park in Kalisz founded in 1798. Boulevards and paths in Łazienki Park in Warsaw surround Palace on the Water. The medieval port crane, called Żuraw, over Motława river, the junction of two boulevards - Długie Pobrzeże and Rybackie Pobrzeże - is the symbol of the medieval harbour of Gdańsk. The Old Town Promenade (Promenada Staromiejska) in Wrocław was built on the former on the former defensive fortifications along the City Moat and a small section along the Oder river. The boulevard in Kasprowicz Park in Szczecin leads along Rusałka Lake from the City Hall area to The Summer Theater (Teatr Letni) and then to Różanka Rose Garden and the forest of Puszcza Wkrzańska. The scenic above ground promenade in Augustów enables the observation of the Augustów Canal and national roads 8 and 16.

Clean Ponds in the wide median green of Chistoprudny Boulevard, Moscow, Russia

The dictionary defines boulevard as a wide green strip in the middle of a city street or on the embankment.[3] Historical Boulevard Ring in Moscow emerged on the site of the former White City walls (demolished in the 1760s and 1770s) before the Fire of 1812, starting with Tverskoy Boulevard in 1796.[4] The whole ring was replanted and rebuilt after the fire, in the 1820s; together with the embankments of Moskva River the boulevards form the second centremost city ring.

Green boulevards of that period were terminated with corner hotel and shop buildings, most of them eventually demolished to make way for street traffic. Garden Ring, developed in the middle of the 19th century, had traditional median boulevards in its western part and side gardens in the east (streets with side strips of green, even those separating main traffic and frontage roads, are not usually considered boulevards).

Street names of Saint Petersburg evolved differently: median greens of major avenues were called boulevards, but the avenues themselves typically were and still are called prospekts (i.e. Bolshoy Prospekt of Vasilievsky Island).

Owing to city planning and physical geography, the UK has only a few boulevards. Glasgow's Mosspark Boulevard, a former segregated tram and car wide road along Bellahouston Park, and Great Western Road, colloqially known as 'The Boulevard' north of the River, is a good example, a mostly dual carriageway road running to the outer suburbs passing through the fashionable West End district, with many shops and bars dotted along the route.

After the Great Fire of London, London was supposed to be formed of straight boulevards, squares and plazas which are seen in mainland Europe, but due to land ownership issues these plans never came to fruition. Boulevards in London are rare but examples, such as Blackfriars Road, do exist. Milton Keynes, Buckinghamshire, is one of only a handful of examples where boulevards are a key feature. This is due to Milton Keynes being built as a modern new town in the 1960s.

Nottingham (and to a lesser extent, Leicester) also have extensive networks of boulevards, although some lower-capacity highways are named boulevards even when they are streets; for example Gilbert Boulevard, Arnold[5] (Asquith Way/Boulevard, West Knighton).

Furthermore, the north-west town of Warrington in Cheshire has a large number of boulevards, some more recent than others. Lining the Gemini Retail Park in Warrington is Europa Boulevard with the traditional tree lined pavements and two-lane traffic. Also, on the recent housing development, Chapelford - built on the old Burtonwood Airbase site, are a number of boulevards such as Boston and Santa Rosa Boulevard, built in reference to the American history associated from World War II on the site.

Barbaros Boulevard in Istanbul, Turkey

Barbaros Boulevard is opened in 1958 due to new city planning in Istanbul. Ankara also has a lot of boulevards.

View of Mexico City's Paseo de la Reforma from Castillo de Chapultepec.

In the Dominican Republic, more specifically in Greater Santo Domingo there is the Winston Churchill and 27 de Febrero Boulevard in Downtown Santo Domingo and Las Americas Boulevard in Santo Domingo Este. These boulevards are known for their wide median with plazas and trees on it.

Paseo de la Reforma (English: "Reform Promenade") is a 12 kilometer long boulevard in Mexico City, Mexico that runs in a straight line, cutting diagonally across the city. It runs from Chapultepec Park, then passes alongside the Torre Mayor (currently Latin America's tallest building), continues through the fashionable Zona Rosa and then to the Zócalo by Juárez Avenue and Francisco I. Madero Street. One of the most famous monuments of the Paseo is El Ángel de la Independencia – a tall column with a gilded statue of a Winged Victory on its top and marble statues at its base depicting the heroes of the Mexican War of Independence.

The Paseo de la Reforma was designed in the 1860s during the Second Mexican Empire by the Austrian military officer and engineer Ferdinand von Rosenzweig on the orders of Maximilian I of Mexico. He wanted to connect his imperial residence, Chapultepec Castle, to the Palacio Nacional in the city's center. When it was inaugurated, it was named the Paseo de la Emperatriz (The Empress's Promenade), after his consort, Empress Carlota of Mexico. The name now commemorates the liberal reforms of 19th-century president Benito Juárez.

Queens Boulevard in New York City Road verge (or Boulevard) in Oak Park, Illinois Roosevelt Boulevard in Philadelphia, Pennsylvania

In many places in the United States of America and Canada, municipalities and developers have adapted the term to refer to arterial roads, not necessarily boulevards in the traditional sense. In California, many so-called "boulevards" extend into the mountains as narrow, winding road segments only two lanes in width. However, boulevards can be any divided highway with at-grade intersections to local streets. They are commonly abbreviated Blvd. Some celebrated examples in California include:

In Chicago, the boulevard system is a network of wide, planted-median boulevards that winds through the south, west, and north sides of the city and includes a ring of parks. Most of the boulevards and parks are 3–6 miles from The Loop. Trucks are not allowed on boulevards in Chicago. Seattle also features a network of boulevards that connect most of the city's public parks to each other, a design recommended by the Olmsted Brothers.[6]

In Philadelphia, the boulevard system includes the length of the Benjamin Franklin Parkway known as the Museum District. It also includes the arterial roadway of the Roosevelt Boulevard and the Southern Boulevard Parkway built as a connecting median of two urban parks, but now also serves as the west roadway entrance of the world class centralized Philadelphia Sports Complex and gatehouse entrance of the Philadelphia Navy Yard in South Philadelphia.

Sometimes, the word "boulevard" is used as a standalone name, as is the case in Atlanta, and Roosevelt Boulevard in the Northeast section of Philadelphia is sometimes referred to, chiefly by locals, simply as "The Boulevard." In Pittsburgh, "The Boulevard of the Allies" runs through and connects major areas of the city.

Kansas City, Missouri and St. Louis, Missouri are famous for having more boulevards and avenues in the world than any city (if the term is used lightly). In Charlotte, North Carolina, Independence Boulevard connects Uptown to the southeastern section of the city, although the westernmost segment is actually a freeway.

New York City has a lot of boulevards, many of which are not designated as such (like Ocean Parkway or Broadway). In the borough of Queens, many important thoroughfares are designated as Boulevards.

Nineteenth century parkways, such as Brooklyn's Ocean Parkway, were often built in the form of boulevards and are informally referred to as such. In some cities, however, the term "boulevard" does not specify a larger, wider, or more important road. "Boulevard" may simply be used as one of many words describing roads in communities containing multiple iterations of the same street name (such as in the Ranchlands district of Calgary, where Ranchlands Boulevard exists side-by-side with Ranchlands Road, Ranchlands Court, Ranchlands Mews, etc.) Nowadays boulevards can be found most anywhere and their original structured meaning has lost almost all meaning.

Lake Shore Boulevard, a six-lane thoroughfare runs along the lakefront in Toronto from Woodbine Avenue in the east to the city limits in the west. The section between Jameson Avenue and the Humber River (the original section), as an example of urban planning, was laid out to provide a pleasant drive with a view of Humber Bay on Lake Ontario and easy access to the park lands by automobile. It was later expanded for commuting.

A famous American example is Las Vegas Boulevard in Las Vegas, Nevada.

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Melbourne has at least four roads named "the Boulevard." These are, generally, long roads with many curves which wind alongside the Yarra River. In addition, the spelling of boulevard with an extra 'e' is common, for example the Southlands Boulevarde shopping centre in southern Perth. Australia post officially abbreviates boulevard as "BVD".[7]

Several Melbourne thoroughfares not named as a boulevard do in fact follow the boulevard configuration of multiple lanes and landscaping. These include St Kilda Road, Royal Parade, Victoria Parade, Flemington Road, and the outer section of Mount Alexander Road.

Boulevards in Sydney include:

Additionally, single-suburb boulevards are situated in Brighton-le-Sands, Cammeray, Cheltenham, Epping, Lidcombe, Lilyfield, Malabar, Newport, Sans Souci, Strathfield and Yagoona.

Construction began on the Orewa Boulevard in March 2009, the works are expected to be complete by February 2010. This boulevard will be approximately 400 m long with Pohutukawa and palm lined footpaths, a wide cycleway will be constructed on the beach side of the road and carparks on the business side. The Orewa Boulevard is a project commissioned by the Rodney District Council with the vision of connecting the CBD to Orewa Beach.

Central Christchurch is surrounded and connected by a series of large boulevards (usually called "avenues" in New Zealand). These include four which surround the central city, Bealey Avenue, Fitzgerald Avenue, Deans Avenue, and Moorhouse Avenue, and also Riccarton Avenue, which traverses the large central city park, Hagley Park. The centre of the city is often described locally as being "within the Four Avenues".[8]

Avenida 9 de Julio in the heart of Buenos Aires, which is the capital city of Argentina, is as wide as 7 lanes in each direction, with 4 further lanes flanking the main boulevard in parallel roads on either side.

View of Bogota’s La Soledad Park Way Boulevard

In Bogotá, ‘’’La Soledad Park Way Boulevard’’’ is an 1 kilometer important boulevard, in the Locality of Teusaquillo located in Bogotá’s City Center and it crosses from the street 35 to street 45.

In the boulevard you can see several monuments and restaurants including Crepes & Waffles, Kokoriko, Subway, The Cheesecake Factory, and the historical hotel ‘’Hotel Park Way Boulevard’’

In Montevideo, Artigas Boulevard is an important avenue (40 metres (130 ft) wide) that encloses the central area.

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https://www.helpwikileaks.co.za/kempton-park/

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For other uses, see Asphalt (disambiguation). Note: The terms bitumen and asphalt are mostly interchangeable, Asphalt Contractors Near Me in Johannesburg except where asphalt is used as a shorthand for asphalt concrete. Natural bitumen from the Dead Sea Refined asphalt The University of Queensland pitch drop experiment, demonstrating the viscosity of asphalt

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Asphalt (/ˈæsˌfɔːlt, -ˌfɑːlt/), also known as bitumen (UK English: /ˈbɪtʃəmən, ˈbɪtjʊmən/,[1] US English: /bɪˈt(j)uːmən, baɪˈt(j)uːmən/)[2] is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used.

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The primary use (70%) of asphalt Asphalt Grinding Companies is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.

The terms “asphalt” and “bitumen” are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, “asphalt” (or “asphalt cement”) is commonly used for a refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called “bitumen”, and geologists worldwide often prefer the term for the naturally occurring variety. Common colloquial usage often refers to various forms of asphalt as “tar”, as in the name of the La Brea Tar Pits.

Michigan left

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Naturally occurring asphalt is sometimes specified by the term “crude bitumen”. Asphalt Contractors Near Me Its viscosity is similar to that of cold molasses[6][7] while the material obtained from the fractional distillation of crude oil boiling at 525 °C (977 °F) is sometimes referred to as “refined bitumen”. The Canadian province of Alberta has most of the world’s reserves of natural asphalt in the Athabasca oil sands, which cover 142,000 square kilometres (55,000 sq mi), an area larger than England.

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The word “asphalt” is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word meaning “asphalt/bitumen/pitch” which perhaps derives from ἀ-, “without” and σφάλλω (sfallō), “make fall”.  New Asphalt Driveway the first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall.[11] From the Greek, the word passed into late Latin, and thence into French (asphalte) and English (“asphaltum” and “asphalt”). In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the “asphaltic concrete” used to pave roads.

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The expression “bitumen” originated in the Sanskrit words jatu, meaning “pitch”, and jatu-krit, meaning “pitch creating” or “pitch producing” (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally gwitu-men (pertaining to pitch), and by others, pixtumens (exuding or bubbling pitch), which was subsequently shortened to bitumen, thence passing via French into English. From the same root is derived the Anglo-Saxon word cwidu (mastix), the German word Kitt (cement or mastic) and the old Norse word kvada.

In British English, “bitumen” is used instead of “asphalt”. The word “asphalt” is instead used to refer to asphalt concrete, a mixture of construction aggregate and asphalt itself (also called “tarmac” in common parlance). Bitumen mixed with clay was usually called “asphaltum”,[13] but the term is less commonly used today.[citation needed]

Sealcoat

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In Australian English, “bitumen” is often used as the generic term for road surfaces.

In American English, “asphalt” is equivalent to the British “bitumen”. However, “asphalt” is also commonly used as a shortened form of “asphalt concrete” (therefore equivalent to the British “asphalt” or “tarmac”).

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In Canadian English, the word “bitumen” is used to refer to the vast Canadian deposits of extremely heavy crude oil,[14] while “asphalt” is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as “dilbit” in the Canadian petroleum industry, while bitumen “upgraded” to synthetic crude oil is known as “syncrude”, and syncrude blended with bitumen is called “synbit”.[15]

“Bitumen” is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. “Bituminous rock” is a form of sandstone impregnated with bitumen. The tar sands of Alberta, Canada are a similar material.

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Neither of the terms “asphalt” or “bitumen” should be confused with tar or coal tars.[further explanation needed]

See also: Asphaltene

The components of asphalt include four main classes of compounds:

The naphthene aromatics and polar aromatics are typically the majority components. Most natural bitumens also contain organosulfur compounds, resulting in an overall sulfur content of up to 4%. Nickel and vanadium are found at <10 parts per million, as is typical of some petroleum.

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The substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase.[16] “It is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large”.

Asphalt may be confused with coal tar, which is a visually similar black, thermoplastic material produced by the destructive distillation of coal. During the early and mid-20th century, when town gas was produced, coal tar was a readily available byproduct and extensively used as the binder for road aggregates. The addition of coal tar to macadam roads led to the word “tarmac”, which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, asphalt has completely overtaken the use of coal tar in these applications. Other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. “Pitch” is another term sometimes informally used at times to refer to asphalt, as in Pitch Lake.

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Bituminous outcrop of the Puy de la Poix, Clermont-Ferrand, France

The majority of asphalt used commercially is obtained from petroleum.[18] Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.

Natural deposits of bitumen include lakes such as the Pitch Lake in Trinidad and Tobago and Lake Bermudez in Venezuela. Natural seeps occur in the La Brea Tar Pits and in the Dead Sea.

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Bitumen also occurs in unconsolidated sandstones known as “oil sands” in Alberta, Canada, and the similar “tar sands” in Utah, US. The Canadian province of Alberta has most of the world’s reserves, in three huge deposits covering 142,000 square kilometres (55,000 sq mi), an area larger than England or New York state. These bituminous sands contain 166 billion barrels (26.4×10^9 m3) of commercially established oil reserves, giving Canada the third largest oil reserves in the world. Although historically it was used without refining to pave roads, nearly all of the output is now used as raw material for oil refineries in Canada and the United States.

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The world’s largest deposit of natural bitumen, known as the Athabasca oil sands, is located in the McMurray Formation of Northern Alberta. This formation is from the early Cretaceous, and is composed of numerous lenses of oil-bearing sand with up to 20% oil.[19] Isotopic studies show the oil deposits to be about 110 million years old.[20] Two smaller but still very large formations occur in the Peace River oil sands and the Cold Lake oil sands, to the west and southeast of the Athabasca oil sands, respectively. Of the Alberta deposits, only parts of the Athabasca oil sands are shallow enough to be suitable for surface mining. The other 80% has to be produced by oil wells using enhanced oil recovery techniques like steam-assisted gravity drainage.

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Much smaller heavy oil or bitumen deposits also occur in the Uinta Basin in Utah, US. The Tar Sand Triangle deposit, for example, is roughly 6% bitumen.

Bitumen may occur in hydrothermal veins. An example of this is within the Uinta Basin of Utah, in the US, where there is a swarm of laterally and vertically extensive veins composed of a solid hydrocarbon termed Gilsonite. These veins formed by the polymerization and solidification of hydrocarbons that were mobilized from the deeper oil shales of the Green River Formation during burial and diagenesis.

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Bitumen is similar to the organic matter in carbonaceous meteorites.[23] However, detailed studies have shown these materials to be distinct.[24] The vast Alberta bitumen resources are considered to have started out as living material from marine plants and animals, mainly algae, that died millions of years ago when an ancient ocean covered Alberta. They were covered by mud, buried deeply over time, and gently cooked into oil by geothermal heat at a temperature of 50 to 150 °C (120 to 300 °F). Due to pressure from the rising of the Rocky Mountains in southwestern Alberta, 80 to 55 million years ago, the oil was driven northeast hundreds of kilometres and trapped into underground sand deposits left behind by ancient river beds and ocean beaches, thus forming the oil sands.

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The use of natural bitumen for waterproofing, and as an adhesive dates at least to the fifth millennium BC, with a crop storage basket discovered in Mehrgarh, of the Indus Valley Civilization, lined with it.[25] By the 3rd millennia BC refined rock asphalt was in use, in the region, and was used to waterproof the Great Bath, Mohenjo-daro.

In the ancient Middle East, the Sumerians used natural bitumen deposits for mortar between bricks and stones, to cement parts of carvings, such as eyes, into place, for ship caulking, and for waterproofing.[3] The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon.

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The 1 kilometre (0.62 mi) long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis (ca. 800 BC) was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent.

Bitumen was used by ancient Egyptians to embalm mummies.[3][28] The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians’ primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake).

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Approximately 40 AD, Dioscorides described the Dead Sea material as Judaicum bitumen, and noted other places in the region where it could be found.[29] The Sidon bitumen is thought to refer to material found at Hasbeya.[30] Pliny refers also to bitumen being found in Epirus. It was a valuable strategic resource, the object of the first known battle for a hydrocarbon deposit—between the Seleucids and the Nabateans in 312 BC.

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In the ancient Far East, natural bitumen was slowly boiled to get rid of the higher fractions, leaving a thermoplastic material of higher molecular weight that when layered on objects became quite hard upon cooling. This was used to cover objects that needed waterproofing,[3] such as scabbards and other items. Statuettes of household deities were also cast with this type of material in Japan, and probably also in China.

In North America, archaeological recovery has indicated bitumen was sometimes used to adhere stone projectile points to wooden shafts.[32] In Canada, aboriginal people used bitumen seeping out of the banks of the Athabasca and other rivers to waterproof birch bark canoes, and also heated it in smudge pots to ward off mosquitoes in the summer.

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In 1553, Pierre Belon described in his work Observations that pissasphalto, a mixture of pitch and bitumen, was used in the Republic of Ragusa (now Dubrovnik, Croatia) for tarring of ships.

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An 1838 edition of Mechanics Magazine cites an early use of asphalt in France. A pamphlet dated 1621, by “a certain Monsieur d’Eyrinys, states that he had discovered the existence (of asphaltum) in large quantities in the vicinity of Neufchatel”, and that he proposed to use it in a variety of ways – “principally in the construction of air-proof granaries, and in protecting, by means of the arches, the water-courses in the city of Paris from the intrusion of dirt and filth”, which at that time made the water unusable. “He expatiates also on the excellence of this material for forming level and durable terraces” in palaces, “the notion of forming such terraces in the streets not one likely to cross the brain of a Parisian of that generation”.

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But the substance was generally neglected in France until the revolution of 1830. In the 1830s there was a surge of interest, and asphalt became widely used “for pavements, flat roofs, and the lining of cisterns, and in England, some use of it had been made of it for similar purposes”. Its rise in Europe was “a sudden phenomenon”, after natural deposits were found “in France at Osbann (Bas-Rhin), the Parc (Ain) and the Puy-de-la-Poix (Puy-de-Dôme)”, although it could also be made artificially.[35] One of the earliest uses in France was the laying of about 24,000 square yards of Seyssel asphalt at the Place de la Concorde in 1835.

Among the earlier uses of bitumen in the United Kingdom was for etching. William Salmon’s Polygraphice (1673) provides a recipe for varnish used in etching, consisting of three ounces of virgin wax, two ounces of mastic, and one ounce of asphaltum.[37] By the fifth edition in 1685, he had included more asphaltum recipes from other sources.

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The first British patent for the use of asphalt was “Cassell’s patent asphalte or bitumen” in 1834.[35] Then on 25 November 1837, Richard Tappin Claridge patented the use of Seyssel asphalt (patent #7849), for use in asphalte pavement,[39][40] having seen it employed in France and Belgium when visiting with Frederick Walter Simms, who worked with him on the introduction of asphalt to Britain.[41][42] Dr T. Lamb Phipson writes that his father, Samuel Ryland Phipson, a friend of Claridge, was also “instrumental in introducing the asphalte pavement (in 1836)”.[43] Indeed, mastic pavements had been previously employed at Vauxhall by a competitor of Claridge, but without success.

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Claridge obtained a patent in Scotland on 27 March 1838, and obtained a patent in Ireland on 23 April 1838. In 1851, extensions for the 1837 patent and for both 1838 patents were sought by the trustees of a company previously formed by Claridge. Claridge’s Patent Asphalte Company—formed in 1838 for the purpose of introducing to Britain “Asphalte in its natural state from the mine at Pyrimont Seysell in France”,—”laid one of the first asphalt pavements in Whitehall”.  Trials were made of the pavement in 1838 on the footway in Whitehall, the stable at Knightsbridge Barracks,”and subsequently on the space at the bottom of the steps leading from Waterloo Place to St. James Park”. “The formation in 1838 of Claridge’s Patent Asphalte Company (with a distinguished list of aristocratic patrons, and Marc and Isambard Brunel as, respectively, a trustee and consulting engineer), gave an enormous impetus to the development of a British asphalt industry”.[45] “By the end of 1838, at least two other companies, Robinson’s and the Bastenne company, were in production”,[50] with asphalt being laid as paving at Brighton, Herne Bay, Canterbury, Kensington, the Strand, and a large floor area in Bunhill-row, while meantime Claridge’s Whitehall paving “continue(d) in good order”.

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Asphalt Surfacing Company Price Macadam country road[dubious – discuss]

Macadam is a type of road construction, pioneered by Scottish engineer John Loudon McAdam around 1820, in which single-sized crushed stone layers of small angular stones are placed in shallow lifts and compacted thoroughly. A binding layer of stone dust (crushed stone from the original material) may form; it may also, after rolling, be covered with a binder to keep dust and stones together. The method simplified what had been considered state of the art at that point.

Pierre-Marie-Jérôme Trésaguet is sometimes considered the first person to bring post-Roman science to road building. A Frenchman from an engineering family, he worked paving roads in Paris from 1757 to 1764. As chief engineer of road construction of Limoges, he had opportunity to develop a better and cheaper method of road construction. In 1775, Tresaguet became engineer-general and presented his answer for road improvement in France, which soon became standard practice there.[1]

Trésaguet had recommended a roadway consisting of three layers of stones laid on a crowned subgrade with side ditches for drainage. The first two layers consisted of angular hand-broken aggregate, maximum size 3 inches (7.6 cm), to a depth of about 8 inches (20 cm). The third layer was about 2 inches (5 cm) thick with a maximum aggregate size of 1 inch (2.5 cm).[2] This top level surface permitted a smoother shape and protected the larger stones in the road structure from iron wheels and horse hooves. To keep the running surface level with the countryside, this road was put in a trench, which created drainage problems. These problems were addressed by changes that included digging deep side ditches, making the surface as solid as possible, and constructing the road with a difference in elevation (height) between the two edges, that difference being referred to interchangeably as the road's camber or cross slope.[2]

Laying Telford paving in Aspinwall, Pennsylvania, 1908

Thomas Telford, born in Dumfriesshire Scotland,[3] was a surveyor and engineer who applied Tresaguet's road building theories. In 1801 Telford worked for the British Commission of Highlands Roads and Bridges. He became director of the Holyhead Road Commission between 1815 and 1830. Telford extended Tresaguet's theories, but emphasized high-quality stone. He recognized that some of the road problems of the French could be avoided by using cubical stone blocks.[4]

Telford used roughly 12 in × 10 in × 6 in (30 cm × 25 cm × 15 cm) partially shaped paving stones (pitchers), with a slight flat face on the bottom surface. He turned the other faces more vertically than Tresaguet's method. The longest edge was arranged crossways to the traffic direction, and the joints were broken in the method of conventional brickwork, but with the smallest faces of the pitcher forming the upper and lower surfaces.[4]

Broken stone was wedged into the spaces between the tapered perpendicular faces to provide the layer with good lateral control. Telford kept the natural formation level and used masons to camber the upper surface of the blocks. He placed a 6-inch (15 cm) layer of stone no bigger than 6 cm (2.4 in) on top of the rock foundation. To finish the road surface he covered the stones with a mixture of gravel and broken stone. This structure came to be known as "Telford pitching." Telford's road depended on a resistant structure to prevent water from collecting and corroding the strength of the pavement. Telford raised the pavement structure above ground level whenever possible.

Where the structure could not be raised, Telford drained the area surrounding the roadside. Previous road builders in Britain ignored drainage problems and Telford's rediscovery of these principles was a major contribution to road construction.[5] Though notably of around the same time, John Metcalf was a strong advocate that drainage was in fact an important factor to road construction, and astonished colleagues by building dry roads through marshland. He accomplished this by installing a layer of brushwood and heather.

John Loudon McAdam (1756–1836)[6]

John Loudon McAdam was born in Ayr, Scotland, in 1756. In 1787, he became a trustee of the Ayrshire Turnpike in the Scottish Lowlands and during the next seven years this hobby became an obsession. He moved to Bristol, England, in 1802 and became a Commissioner for Paving in 1806.[7] On 15 January 1816, he was elected Surveyor-General of roads for the Turnpike Trust and was now responsible for 149 miles of road.[7] He then put his ideas about road construction into practice, the first 'macadamised' stretch of road being Marsh Road at Ashton Gate, Bristol.[7] He also began to actively propagate his ideas in two booklets called Remarks (or Observations) on the Present System of Roadmaking, (which ran nine editions between 1816 and 1827) and A Practical Essay on the Scientific Repair and Preservation of Public Roads, published in 1819.[8]

Photograph of macadam road, ca 1850s, Nicolaus, California

McAdam's method was simpler, yet more effective at protecting roadways: he discovered that massive foundations of rock upon rock were unnecessary, and asserted that native soil alone would support the road and traffic upon it, as long as it was covered by a road crust that would protect the soil underneath from water and wear.[9]

Unlike Telford and other road builders of the time, McAdam laid his roads as level as possible. His 30-foot-wide (9.1 m) road required only a rise of 3 inches (7.6 cm) from the edges to the centre. Cambering and elevation of the road above the water table enabled rain water to run off into ditches on either side.[10]

Size of stones was central to the McAdam's road building theory. The lower 20-centimetre (7.9 in) road thickness was restricted to stones no larger than 7.5 centimetres (3.0 in). The upper 5-centimetre (2.0 in) layer of stones was limited to 2 centimetres (0.79 in) size and stones were checked by supervisors who carried scales. A workman could check the stone size himself by seeing if the stone would fit into his mouth. The importance of the 2 cm stone size was that the stones needed to be much smaller than the 10 cm width of the iron carriage tyres that travelled on the road.[5]

McAdam believed that the "proper method" of breaking stones for utility and rapidity was accomplished by people sitting down and using small hammers, breaking the stones so that none of them was larger than six ounces in weight. He also wrote that the quality of the road would depend on how carefully the stones were spread on the surface over a sizeable space, one shovelful at a time.[11]

McAdam directed that no substance that would absorb water and affect the road by frost should be incorporated into the road. Neither was anything to be laid on the clean stone to bind the road. The action of the road traffic would cause the broken stone to combine with its own angles, merging into a level, solid surface that would withstand weather or traffic.[12]

Through his road-building experience, McAdam had learned that a layer of broken angular stones would act as a solid mass and would not require the large stone layer previously used to build roads. Keeping the surface stones smaller than the tyre width made a good running surface for traffic. The small surface stones also provided low stress on the road, so long as it could be kept reasonably dry.[13]

Construction of the first macadamized road in the United States (1823). In the foreground, workers are breaking stones "so as not to exceed 6 ounces [170 g] in weight or to pass a two-inch [5 cm] ring".[14][15][16]

The first macadam road built in the United States was constructed between Hagerstown and Boonsboro, Maryland and was named at the time Boonsborough Turnpike Road. This was the last section of unimproved road between Baltimore on the Chesapeake Bay to Wheeling on the Ohio River. Stagecoaches traveling the Hagerstown to Boonsboro road in the winter took 5 to 7 hours to cover the 10-mile (16 km) stretch.[15][16] This road was completed in 1823, using McAdam's road techniques, except that the finished road was compacted with a cast-iron roller instead of relying on road traffic for compaction.[17][15][16] The second American road built using McAdam principles was the Cumberland Road which was 73 miles (117 km) long and was completed in 1830 after five years of work.[15][16]

McAdam's renown is due to his effective and economical construction, which was a great improvement over the methods used by his generation. He emphasized that roads could be constructed for any kind of traffic, and he helped to alleviate the resentment travelers felt toward increasing traffic on the roads. His legacy lies in his advocacy of effective road maintenance and management. He advocated a central road authority and the trained professional official, who could be paid a salary that would keep him from corruption. This professional could give his entire time to his duties and be held responsible for his actions.[18]

McAdam's road building technology was applied to roads by other engineers. One of these engineers was Richard Edgeworth, who filled the gaps between the surface stones with a mixture of stone dust and water, providing a smoother surface for the increased traffic using the roads.[19] This basic method of construction is sometimes known as water-bound macadam. Although this method required a great deal of manual labour, it resulted in a strong and free-draining pavement. Roads constructed in this manner were described as "macadamized."[19]

New macadam road construction at McRoberts, Kentucky: pouring tar. 1926

With the advent of motor vehicles, dust became a serious problem on macadam roads. The area of low air pressure created under fast-moving vehicles sucked dust from the road surface, creating dust clouds and a gradual unraveling of the road material.[20] This problem was approached by spraying tar on the surface to create tar-bound macadam. On March 13, 1902 in Monaco, a Swiss doctor, Ernest Guglielminetti, came upon the idea of using tar from Monaco's gasworks for binding the dust.[21] Later a mixture of coal tar and ironworks slag, patented by Edgar Purnell Hooley as tarmac, was introduced.

A more durable road surface (modern mixed asphalt pavement) sometimes referred to in the US as blacktop, was introduced in the 1920s. This pavement method mixed the aggregates into the asphalt with the binding material before they were laid. The macadam surface method laid the stone and sand aggregates on the road and then sprayed it with the binding material.[22] While macadam roads have now been resurfaced in most developed countries, some are preserved along stretches of roads such as the United States' National Road.[citation needed]

Because of the historic use of macadam as a road surface, roads in some parts of the United States (as parts of Pennsylvania) are often referred to as macadam, even though they might be made of asphalt or concrete. Similarly, the term "tarmac" is sometimes colloquially misapplied to asphalt roads or aircraft runways.[23]

Alley

Asphalt Surfacing Company Price Moderate to severe Fatigue cracking.

Crocodile cracking, also called alligator cracking and perhaps misleadingly fatigue cracking, is a common type of distress in asphalt pavement. The following is more closely related to fatigue cracking which is characterized by interconnecting or interlaced cracking in the asphalt layer resembling the hide of a crocodile.[1] Cell sizes can vary in size up to 11.80 inches (300 mm) across, but are typically less than 5.90 inches (150 mm) across. Fatigue cracking is generally a loading failure,[1] but numerous factors can contribute to it. It is often a sign of sub-base failure, poor drainage, or repeated over-loadings. It is important to prevent fatigue cracking, and repair as soon as possible, as advanced cases can be very costly to repair and can lead to formation of potholes or premature pavement failure.

It is usually studied under the transportation section of civil engineering.

Fatigue cracking is an asphalt pavement distress most often instigated by failure of the surface due to traffic loading. However, fatigue cracking can be greatly influenced by environmental and other effects while traffic loading remains the direct cause. Frequently, overloading happens because the base or subbase inadequately support the surface layer and subsequently cannot handle loads that it would normally endure.[2] There are many ways that the subbase or base can be weakened.

Poor drainage in the road bed is a frequent cause of this degradation of the base or subgrade.[1] A heavy spring thaw, similarly to poor drainage, can weaken the base course, leading to fatigue cracking.[1]

Stripping or raveling is another possible cause of fatigue cracking. Stripping occurs when poor adhesion between asphalt and aggregate allows the aggregate at the surface to dislodge. If left uncorrected, this reduces the thickness of the pavement, reducing the affected portion's ability to carry its designed loading.[1] This can cause fatigue cracking to develop rapidly, as overloading will happen with loads of less magnitude or frequency.

Edge cracking is the formation of crescent-shaped cracks near the edge of a road.[3] It is caused by lack of support of the road edge, sometimes due to poorly drained or weak shoulders. If left untreated, additional cracks will form until it resembles fatigue cracking.[3] Like wheel-path fatigue cracking, poor drainage is a main cause of edge cracking, as it weakens the base, which hastens the deterioration of the pavement.[4] Water ponding (a buildup of water which can also be called puddling) happens more frequently near the edge than in the center of the road path, as roads are usually sloped to prevent in-lane ponding. This leads to excess moisture in the shoulders and subbase at the road edge. Edge cracking differs from fatigue cracking in that the cracks form from the top down, where fatigue cracks usually start at the bottom and propagate to the surface.

Fatigue cracking manifests itself initially as longitudinal cracking (cracks along the direction of the flow of traffic) in the top layer of the asphalt.[5] These cracks are initially thin and sparsely distributed. If further deterioration is allowed, these longitudinal cracks are connected by transverse cracks to form sharp sided, prismatic pieces. This interlaced cracking pattern resembles the scales on the back of a crocodile or alligator, hence the nickname, crocodile cracking.

More severe cases involve pumping of fines, spalling, and loose pieces of pavement. The most severe cases of fatigue cracking often occur with other pavement distresses, but are exemplified by: potholes,[1] large cracks(3/8" or larger), and severely spalled edges.[4]

There are many different ways to measure fatigue cracking, but in general a pavement distress manual or index will be used. For example, the Pavement Condition Index is widely used to quantify the overall level of distress and condition of a section of road. Measurement of fatigue cracking specifically (and pavement distress in general) is necessary to determine the overall condition of a road, and for determination of a time-line for rehabilitation and/or repair. There are many other rating systems, and many rating systems currently in use are based on the AASHO Road Test.

There are two important criteria to take into account when measuring fatigue cracking. The first is the extent of the cracking. This is the amount of road surface area which is affected by this pavement distress. The second criterion is the severity of the cracking.[6] Severity, which has been discussed above, refers to how far the cracking has progressed, and is often directly a function of crack width.[6] Severity may be rated numerically, or given a rating from "low" to "severe". The rating may be entered into a pavement management system, which will suggest a priority and method for the repair.

Systems have been developed that detect fatigue cracking and other types of pavement distress automatically.[7] They measure the severity and frequency of alligator cracking on the road-path. One such machine is the road surface profilometer, which is mounted on a vehicle and measures the profile of the road surface while it is moving down the roadway.

Preventing fatigue cracking can be as simple as preventing the common causes. For example, reducing overloading on an asphalt pavement or improving drainage[2] can prevent fatigue cracking in many cases. Prevention primarily depends on designing and constructing the pavement and subbase to support the expected traffic loads, and providing good drainage to keep water out of the subbase.

A good strategy to prevent overloading, which is a main cause of fatigue cracking, is to increase the depth of the asphalt layer. According to certain researchers, pavements that exceed a certain minimum strength or thickness can hypothetically handle infinitely many loads without showing structural defects, including fatigue cracking.[1] These pavements are called perpetual pavements or long-term performance pavements (LTPP).

When repairing pavement affected by fatigue cracking, the main cause of the distress should be determined. However, often the specific cause is fairly difficult to determine, and prevention is therefore correspondingly difficult. Any investigation should involve digging a pit or coring the pavement and subbase to determine the pavement's structural makeup as well as determining whether or not subsurface moisture is a contributing factor.[1] The repair needed also differs based on the severity and extent of the cracking.

In the early stages, sealing cracks with crack sealant limits further deterioration of the subgrade due to moisture penetration. Small areas may be repaired by removal of the affected area, and replacement with new base and asphalt surface.[2] Once the damage has progressed or the affected area is large and extensive, a structural asphalt overlay or complete reconstruction is necessary to ensure structural integrity. Proper repair may include first sealing cracks with crack sealant, installing paving fabric over a tack coat, or milling the damaged asphalt. An overlay of hot mix asphalt is then placed over the completed repair. [2]

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For other uses, see Asphalt (disambiguation). Note: The terms bitumen and asphalt are mostly interchangeable, Asphalt Sealing Contractors in River Club except where asphalt is used as a shorthand for asphalt concrete. Natural bitumen from the Dead Sea Refined asphalt The University of Queensland pitch drop experiment, demonstrating the viscosity of asphalt

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Asphalt (/ˈæsˌfɔːlt, -ˌfɑːlt/), also known as bitumen (UK English: /ˈbɪtʃəmən, ˈbɪtjʊmən/,[1] US English: /bɪˈt(j)uːmən, baɪˈt(j)uːmən/)[2] is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used.

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The primary use (70%) of asphalt Driveway Pavers Companies is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.

The terms “asphalt” and “bitumen” are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, “asphalt” (or “asphalt cement”) is commonly used for a refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called “bitumen”, and geologists worldwide often prefer the term for the naturally occurring variety. Common colloquial usage often refers to various forms of asphalt as “tar”, as in the name of the La Brea Tar Pits.

Road surface

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Naturally occurring asphalt is sometimes specified by the term “crude bitumen”. Asphalt Sealing Contractors Its viscosity is similar to that of cold molasses[6][7] while the material obtained from the fractional distillation of crude oil boiling at 525 °C (977 °F) is sometimes referred to as “refined bitumen”. The Canadian province of Alberta has most of the world’s reserves of natural asphalt in the Athabasca oil sands, which cover 142,000 square kilometres (55,000 sq mi), an area larger than England.

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The word “asphalt” is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word meaning “asphalt/bitumen/pitch” which perhaps derives from ἀ-, “without” and σφάλλω (sfallō), “make fall”.  Asphalt And Paving Companies Near Me the first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall.[11] From the Greek, the word passed into late Latin, and thence into French (asphalte) and English (“asphaltum” and “asphalt”). In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the “asphaltic concrete” used to pave roads.

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The expression “bitumen” originated in the Sanskrit words jatu, meaning “pitch”, and jatu-krit, meaning “pitch creating” or “pitch producing” (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally gwitu-men (pertaining to pitch), and by others, pixtumens (exuding or bubbling pitch), which was subsequently shortened to bitumen, thence passing via French into English. From the same root is derived the Anglo-Saxon word cwidu (mastix), the German word Kitt (cement or mastic) and the old Norse word kvada.

In British English, “bitumen” is used instead of “asphalt”. The word “asphalt” is instead used to refer to asphalt concrete, a mixture of construction aggregate and asphalt itself (also called “tarmac” in common parlance). Bitumen mixed with clay was usually called “asphaltum”,[13] but the term is less commonly used today.[citation needed]

Sidewalk

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In Australian English, “bitumen” is often used as the generic term for road surfaces.

In American English, “asphalt” is equivalent to the British “bitumen”. However, “asphalt” is also commonly used as a shortened form of “asphalt concrete” (therefore equivalent to the British “asphalt” or “tarmac”).

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In Canadian English, the word “bitumen” is used to refer to the vast Canadian deposits of extremely heavy crude oil,[14] while “asphalt” is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as “dilbit” in the Canadian petroleum industry, while bitumen “upgraded” to synthetic crude oil is known as “syncrude”, and syncrude blended with bitumen is called “synbit”.[15]

“Bitumen” is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. “Bituminous rock” is a form of sandstone impregnated with bitumen. The tar sands of Alberta, Canada are a similar material.

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Neither of the terms “asphalt” or “bitumen” should be confused with tar or coal tars.[further explanation needed]

See also: Asphaltene

The components of asphalt include four main classes of compounds:

The naphthene aromatics and polar aromatics are typically the majority components. Most natural bitumens also contain organosulfur compounds, resulting in an overall sulfur content of up to 4%. Nickel and vanadium are found at <10 parts per million, as is typical of some petroleum.

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The substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase.[16] “It is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large”.

Asphalt may be confused with coal tar, which is a visually similar black, thermoplastic material produced by the destructive distillation of coal. During the early and mid-20th century, when town gas was produced, coal tar was a readily available byproduct and extensively used as the binder for road aggregates. The addition of coal tar to macadam roads led to the word “tarmac”, which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, asphalt has completely overtaken the use of coal tar in these applications. Other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. “Pitch” is another term sometimes informally used at times to refer to asphalt, as in Pitch Lake.

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Bituminous outcrop of the Puy de la Poix, Clermont-Ferrand, France

The majority of asphalt used commercially is obtained from petroleum.[18] Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.

Natural deposits of bitumen include lakes such as the Pitch Lake in Trinidad and Tobago and Lake Bermudez in Venezuela. Natural seeps occur in the La Brea Tar Pits and in the Dead Sea.

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Bitumen also occurs in unconsolidated sandstones known as “oil sands” in Alberta, Canada, and the similar “tar sands” in Utah, US. The Canadian province of Alberta has most of the world’s reserves, in three huge deposits covering 142,000 square kilometres (55,000 sq mi), an area larger than England or New York state. These bituminous sands contain 166 billion barrels (26.4×10^9 m3) of commercially established oil reserves, giving Canada the third largest oil reserves in the world. Although historically it was used without refining to pave roads, nearly all of the output is now used as raw material for oil refineries in Canada and the United States.

Permeable paving

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The world’s largest deposit of natural bitumen, known as the Athabasca oil sands, is located in the McMurray Formation of Northern Alberta. This formation is from the early Cretaceous, and is composed of numerous lenses of oil-bearing sand with up to 20% oil.[19] Isotopic studies show the oil deposits to be about 110 million years old.[20] Two smaller but still very large formations occur in the Peace River oil sands and the Cold Lake oil sands, to the west and southeast of the Athabasca oil sands, respectively. Of the Alberta deposits, only parts of the Athabasca oil sands are shallow enough to be suitable for surface mining. The other 80% has to be produced by oil wells using enhanced oil recovery techniques like steam-assisted gravity drainage.

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Much smaller heavy oil or bitumen deposits also occur in the Uinta Basin in Utah, US. The Tar Sand Triangle deposit, for example, is roughly 6% bitumen.

Bitumen may occur in hydrothermal veins. An example of this is within the Uinta Basin of Utah, in the US, where there is a swarm of laterally and vertically extensive veins composed of a solid hydrocarbon termed Gilsonite. These veins formed by the polymerization and solidification of hydrocarbons that were mobilized from the deeper oil shales of the Green River Formation during burial and diagenesis.

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Bitumen is similar to the organic matter in carbonaceous meteorites.[23] However, detailed studies have shown these materials to be distinct.[24] The vast Alberta bitumen resources are considered to have started out as living material from marine plants and animals, mainly algae, that died millions of years ago when an ancient ocean covered Alberta. They were covered by mud, buried deeply over time, and gently cooked into oil by geothermal heat at a temperature of 50 to 150 °C (120 to 300 °F). Due to pressure from the rising of the Rocky Mountains in southwestern Alberta, 80 to 55 million years ago, the oil was driven northeast hundreds of kilometres and trapped into underground sand deposits left behind by ancient river beds and ocean beaches, thus forming the oil sands.

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The use of natural bitumen for waterproofing, and as an adhesive dates at least to the fifth millennium BC, with a crop storage basket discovered in Mehrgarh, of the Indus Valley Civilization, lined with it.[25] By the 3rd millennia BC refined rock asphalt was in use, in the region, and was used to waterproof the Great Bath, Mohenjo-daro.

In the ancient Middle East, the Sumerians used natural bitumen deposits for mortar between bricks and stones, to cement parts of carvings, such as eyes, into place, for ship caulking, and for waterproofing.[3] The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon.

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The 1 kilometre (0.62 mi) long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis (ca. 800 BC) was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent.

Bitumen was used by ancient Egyptians to embalm mummies.[3][28] The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians’ primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake).

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Approximately 40 AD, Dioscorides described the Dead Sea material as Judaicum bitumen, and noted other places in the region where it could be found.[29] The Sidon bitumen is thought to refer to material found at Hasbeya.[30] Pliny refers also to bitumen being found in Epirus. It was a valuable strategic resource, the object of the first known battle for a hydrocarbon deposit—between the Seleucids and the Nabateans in 312 BC.

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In the ancient Far East, natural bitumen was slowly boiled to get rid of the higher fractions, leaving a thermoplastic material of higher molecular weight that when layered on objects became quite hard upon cooling. This was used to cover objects that needed waterproofing,[3] such as scabbards and other items. Statuettes of household deities were also cast with this type of material in Japan, and probably also in China.

In North America, archaeological recovery has indicated bitumen was sometimes used to adhere stone projectile points to wooden shafts.[32] In Canada, aboriginal people used bitumen seeping out of the banks of the Athabasca and other rivers to waterproof birch bark canoes, and also heated it in smudge pots to ward off mosquitoes in the summer.

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In 1553, Pierre Belon described in his work Observations that pissasphalto, a mixture of pitch and bitumen, was used in the Republic of Ragusa (now Dubrovnik, Croatia) for tarring of ships.

Diverging diamond interchange

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An 1838 edition of Mechanics Magazine cites an early use of asphalt in France. A pamphlet dated 1621, by “a certain Monsieur d’Eyrinys, states that he had discovered the existence (of asphaltum) in large quantities in the vicinity of Neufchatel”, and that he proposed to use it in a variety of ways – “principally in the construction of air-proof granaries, and in protecting, by means of the arches, the water-courses in the city of Paris from the intrusion of dirt and filth”, which at that time made the water unusable. “He expatiates also on the excellence of this material for forming level and durable terraces” in palaces, “the notion of forming such terraces in the streets not one likely to cross the brain of a Parisian of that generation”.

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But the substance was generally neglected in France until the revolution of 1830. In the 1830s there was a surge of interest, and asphalt became widely used “for pavements, flat roofs, and the lining of cisterns, and in England, some use of it had been made of it for similar purposes”. Its rise in Europe was “a sudden phenomenon”, after natural deposits were found “in France at Osbann (Bas-Rhin), the Parc (Ain) and the Puy-de-la-Poix (Puy-de-Dôme)”, although it could also be made artificially.[35] One of the earliest uses in France was the laying of about 24,000 square yards of Seyssel asphalt at the Place de la Concorde in 1835.

Among the earlier uses of bitumen in the United Kingdom was for etching. William Salmon’s Polygraphice (1673) provides a recipe for varnish used in etching, consisting of three ounces of virgin wax, two ounces of mastic, and one ounce of asphaltum.[37] By the fifth edition in 1685, he had included more asphaltum recipes from other sources.

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The first British patent for the use of asphalt was “Cassell’s patent asphalte or bitumen” in 1834.[35] Then on 25 November 1837, Richard Tappin Claridge patented the use of Seyssel asphalt (patent #7849), for use in asphalte pavement,[39][40] having seen it employed in France and Belgium when visiting with Frederick Walter Simms, who worked with him on the introduction of asphalt to Britain.[41][42] Dr T. Lamb Phipson writes that his father, Samuel Ryland Phipson, a friend of Claridge, was also “instrumental in introducing the asphalte pavement (in 1836)”.[43] Indeed, mastic pavements had been previously employed at Vauxhall by a competitor of Claridge, but without success.

Crocodile cracking

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Claridge obtained a patent in Scotland on 27 March 1838, and obtained a patent in Ireland on 23 April 1838. In 1851, extensions for the 1837 patent and for both 1838 patents were sought by the trustees of a company previously formed by Claridge. Claridge’s Patent Asphalte Company—formed in 1838 for the purpose of introducing to Britain “Asphalte in its natural state from the mine at Pyrimont Seysell in France”,—”laid one of the first asphalt pavements in Whitehall”.  Trials were made of the pavement in 1838 on the footway in Whitehall, the stable at Knightsbridge Barracks,”and subsequently on the space at the bottom of the steps leading from Waterloo Place to St. James Park”. “The formation in 1838 of Claridge’s Patent Asphalte Company (with a distinguished list of aristocratic patrons, and Marc and Isambard Brunel as, respectively, a trustee and consulting engineer), gave an enormous impetus to the development of a British asphalt industry”.[45] “By the end of 1838, at least two other companies, Robinson’s and the Bastenne company, were in production”,[50] with asphalt being laid as paving at Brighton, Herne Bay, Canterbury, Kensington, the Strand, and a large floor area in Bunhill-row, while meantime Claridge’s Whitehall paving “continue(d) in good order”.

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Asphalt Repair Costs Macadam country road[dubious – discuss]

Macadam is a type of road construction, pioneered by Scottish engineer John Loudon McAdam around 1820, in which single-sized crushed stone layers of small angular stones are placed in shallow lifts and compacted thoroughly. A binding layer of stone dust (crushed stone from the original material) may form; it may also, after rolling, be covered with a binder to keep dust and stones together. The method simplified what had been considered state of the art at that point.

Pierre-Marie-Jérôme Trésaguet is sometimes considered the first person to bring post-Roman science to road building. A Frenchman from an engineering family, he worked paving roads in Paris from 1757 to 1764. As chief engineer of road construction of Limoges, he had opportunity to develop a better and cheaper method of road construction. In 1775, Tresaguet became engineer-general and presented his answer for road improvement in France, which soon became standard practice there.[1]

Trésaguet had recommended a roadway consisting of three layers of stones laid on a crowned subgrade with side ditches for drainage. The first two layers consisted of angular hand-broken aggregate, maximum size 3 inches (7.6 cm), to a depth of about 8 inches (20 cm). The third layer was about 2 inches (5 cm) thick with a maximum aggregate size of 1 inch (2.5 cm).[2] This top level surface permitted a smoother shape and protected the larger stones in the road structure from iron wheels and horse hooves. To keep the running surface level with the countryside, this road was put in a trench, which created drainage problems. These problems were addressed by changes that included digging deep side ditches, making the surface as solid as possible, and constructing the road with a difference in elevation (height) between the two edges, that difference being referred to interchangeably as the road's camber or cross slope.[2]

Laying Telford paving in Aspinwall, Pennsylvania, 1908

Thomas Telford, born in Dumfriesshire Scotland,[3] was a surveyor and engineer who applied Tresaguet's road building theories. In 1801 Telford worked for the British Commission of Highlands Roads and Bridges. He became director of the Holyhead Road Commission between 1815 and 1830. Telford extended Tresaguet's theories, but emphasized high-quality stone. He recognized that some of the road problems of the French could be avoided by using cubical stone blocks.[4]

Telford used roughly 12 in × 10 in × 6 in (30 cm × 25 cm × 15 cm) partially shaped paving stones (pitchers), with a slight flat face on the bottom surface. He turned the other faces more vertically than Tresaguet's method. The longest edge was arranged crossways to the traffic direction, and the joints were broken in the method of conventional brickwork, but with the smallest faces of the pitcher forming the upper and lower surfaces.[4]

Broken stone was wedged into the spaces between the tapered perpendicular faces to provide the layer with good lateral control. Telford kept the natural formation level and used masons to camber the upper surface of the blocks. He placed a 6-inch (15 cm) layer of stone no bigger than 6 cm (2.4 in) on top of the rock foundation. To finish the road surface he covered the stones with a mixture of gravel and broken stone. This structure came to be known as "Telford pitching." Telford's road depended on a resistant structure to prevent water from collecting and corroding the strength of the pavement. Telford raised the pavement structure above ground level whenever possible.

Where the structure could not be raised, Telford drained the area surrounding the roadside. Previous road builders in Britain ignored drainage problems and Telford's rediscovery of these principles was a major contribution to road construction.[5] Though notably of around the same time, John Metcalf was a strong advocate that drainage was in fact an important factor to road construction, and astonished colleagues by building dry roads through marshland. He accomplished this by installing a layer of brushwood and heather.

John Loudon McAdam (1756–1836)[6]

John Loudon McAdam was born in Ayr, Scotland, in 1756. In 1787, he became a trustee of the Ayrshire Turnpike in the Scottish Lowlands and during the next seven years this hobby became an obsession. He moved to Bristol, England, in 1802 and became a Commissioner for Paving in 1806.[7] On 15 January 1816, he was elected Surveyor-General of roads for the Turnpike Trust and was now responsible for 149 miles of road.[7] He then put his ideas about road construction into practice, the first 'macadamised' stretch of road being Marsh Road at Ashton Gate, Bristol.[7] He also began to actively propagate his ideas in two booklets called Remarks (or Observations) on the Present System of Roadmaking, (which ran nine editions between 1816 and 1827) and A Practical Essay on the Scientific Repair and Preservation of Public Roads, published in 1819.[8]

Photograph of macadam road, ca 1850s, Nicolaus, California

McAdam's method was simpler, yet more effective at protecting roadways: he discovered that massive foundations of rock upon rock were unnecessary, and asserted that native soil alone would support the road and traffic upon it, as long as it was covered by a road crust that would protect the soil underneath from water and wear.[9]

Unlike Telford and other road builders of the time, McAdam laid his roads as level as possible. His 30-foot-wide (9.1 m) road required only a rise of 3 inches (7.6 cm) from the edges to the centre. Cambering and elevation of the road above the water table enabled rain water to run off into ditches on either side.[10]

Size of stones was central to the McAdam's road building theory. The lower 20-centimetre (7.9 in) road thickness was restricted to stones no larger than 7.5 centimetres (3.0 in). The upper 5-centimetre (2.0 in) layer of stones was limited to 2 centimetres (0.79 in) size and stones were checked by supervisors who carried scales. A workman could check the stone size himself by seeing if the stone would fit into his mouth. The importance of the 2 cm stone size was that the stones needed to be much smaller than the 10 cm width of the iron carriage tyres that travelled on the road.[5]

McAdam believed that the "proper method" of breaking stones for utility and rapidity was accomplished by people sitting down and using small hammers, breaking the stones so that none of them was larger than six ounces in weight. He also wrote that the quality of the road would depend on how carefully the stones were spread on the surface over a sizeable space, one shovelful at a time.[11]

McAdam directed that no substance that would absorb water and affect the road by frost should be incorporated into the road. Neither was anything to be laid on the clean stone to bind the road. The action of the road traffic would cause the broken stone to combine with its own angles, merging into a level, solid surface that would withstand weather or traffic.[12]

Through his road-building experience, McAdam had learned that a layer of broken angular stones would act as a solid mass and would not require the large stone layer previously used to build roads. Keeping the surface stones smaller than the tyre width made a good running surface for traffic. The small surface stones also provided low stress on the road, so long as it could be kept reasonably dry.[13]

Construction of the first macadamized road in the United States (1823). In the foreground, workers are breaking stones "so as not to exceed 6 ounces [170 g] in weight or to pass a two-inch [5 cm] ring".[14][15][16]

The first macadam road built in the United States was constructed between Hagerstown and Boonsboro, Maryland and was named at the time Boonsborough Turnpike Road. This was the last section of unimproved road between Baltimore on the Chesapeake Bay to Wheeling on the Ohio River. Stagecoaches traveling the Hagerstown to Boonsboro road in the winter took 5 to 7 hours to cover the 10-mile (16 km) stretch.[15][16] This road was completed in 1823, using McAdam's road techniques, except that the finished road was compacted with a cast-iron roller instead of relying on road traffic for compaction.[17][15][16] The second American road built using McAdam principles was the Cumberland Road which was 73 miles (117 km) long and was completed in 1830 after five years of work.[15][16]

McAdam's renown is due to his effective and economical construction, which was a great improvement over the methods used by his generation. He emphasized that roads could be constructed for any kind of traffic, and he helped to alleviate the resentment travelers felt toward increasing traffic on the roads. His legacy lies in his advocacy of effective road maintenance and management. He advocated a central road authority and the trained professional official, who could be paid a salary that would keep him from corruption. This professional could give his entire time to his duties and be held responsible for his actions.[18]

McAdam's road building technology was applied to roads by other engineers. One of these engineers was Richard Edgeworth, who filled the gaps between the surface stones with a mixture of stone dust and water, providing a smoother surface for the increased traffic using the roads.[19] This basic method of construction is sometimes known as water-bound macadam. Although this method required a great deal of manual labour, it resulted in a strong and free-draining pavement. Roads constructed in this manner were described as "macadamized."[19]

New macadam road construction at McRoberts, Kentucky: pouring tar. 1926

With the advent of motor vehicles, dust became a serious problem on macadam roads. The area of low air pressure created under fast-moving vehicles sucked dust from the road surface, creating dust clouds and a gradual unraveling of the road material.[20] This problem was approached by spraying tar on the surface to create tar-bound macadam. On March 13, 1902 in Monaco, a Swiss doctor, Ernest Guglielminetti, came upon the idea of using tar from Monaco's gasworks for binding the dust.[21] Later a mixture of coal tar and ironworks slag, patented by Edgar Purnell Hooley as tarmac, was introduced.

A more durable road surface (modern mixed asphalt pavement) sometimes referred to in the US as blacktop, was introduced in the 1920s. This pavement method mixed the aggregates into the asphalt with the binding material before they were laid. The macadam surface method laid the stone and sand aggregates on the road and then sprayed it with the binding material.[22] While macadam roads have now been resurfaced in most developed countries, some are preserved along stretches of roads such as the United States' National Road.[citation needed]

Because of the historic use of macadam as a road surface, roads in some parts of the United States (as parts of Pennsylvania) are often referred to as macadam, even though they might be made of asphalt or concrete. Similarly, the term "tarmac" is sometimes colloquially misapplied to asphalt roads or aircraft runways.[23]

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Asphalt Companies Costs A diagram illustrating traffic movements in the interchange Plan of rejected diverging diamond interchange in Findlay, Ohio

A diverging diamond interchange (DDI), also called a double crossover diamond interchange (DCD),[1] is a type of diamond interchange in which the two directions of traffic on the non-freeway road cross to the opposite side on both sides of the bridge at the freeway. It is unusual in that it requires traffic on the freeway overpass (or underpass) to briefly drive on the opposite side of the road from what is customary for the jurisdiction. The crossover "X" sections can either be traffic-light intersections or one-side overpasses to travel above the opposite lanes without stopping, to allow nonstop traffic flow when relatively sparse traffic.

Like the continuous flow intersection, the diverging diamond interchange allows for two-phase operation at all signalized intersections within the interchange. This is a significant improvement in safety, since no long turns (e.g. left turns where traffic drives on the right side of the road) must clear opposing traffic and all movements are discrete, with most controlled by traffic signals.[2] Its at-grade variant can be seen as a two-leg continuous flow intersection.[3]

Additionally, the design can improve the efficiency of an interchange, as the lost time for various phases in the cycle can be redistributed as green time—there are only two clearance intervals (the time for traffic signals to change from green to yellow to red) instead of the six or more found in other interchange designs.

A diverging diamond can be constructed for limited cost, at an existing straight-line bridge, by building crisscross intersections outside the bridge ramps to switch traffic lanes before entering the bridge. The switchover lanes, each with 2 side ramps, introduce a new risk of drivers turning onto an empty, wrong, do-not-enter, exit-lane and driving wrongway down a freeway exit ramp to confront high-speed, oncoming traffic. Studies have analyzed various roadsigns to reduce similar driver errors.

Diverging diamond roads have been used in France since the 1970s. However, the diverging diamond interchange was listed by Popular Science magazine as one of the best innovations in 2009 (engineering category) in "Best of What's New 2009".[4]

Pictures from the first diverging diamond interchange in the United States, in Springfield, Missouri
Top left: Traffic enters the interchange along Missouri Route 13
Top right: Traffic crosses over to the left side of the road
Bottom left: Traffic crosses over Interstate 44
Bottom right:Traffic crosses back over to the right side of the road. Southbound approach to the I-44/Route 13 interchange in Springfield

Prior to 2009 the only known diverging diamond interchanges were in France in the communities of Versailles, Le Perreux-sur-Marne (A4 at N486) and Seclin, all built in the 1970s.[5] (The ramps of the first two have been reconfigured to accommodate ramps of other interchanges, but they continue to function as diverging diamond interchanges.)

Despite the fact that such interchanges already existed, the idea for the DDI was "reinvented" around 2000, inspired by the former "synchronized split-phasing" type freeway-to-freeway interchange between Interstate 95 and I-695 north of Baltimore.[6]

In 2005, the Ohio Department of Transportation (ODOT) considered reconfiguring the existing interchange on Interstate 75 at U.S. Route 224 and State Route 15 west of Findlay as a diverging diamond interchange to improve traffic flow. Had it been constructed, it would have been the first DDI in the United States.[7] By 2006, ODOT had reconsidered, instead adding lanes to the existing overpass.[8][9]

The Missouri Department of Transportation was the first US agency to construct one, in Springfield at the junction between I-44 and Missouri Route 13 (at 37°15′01″N 93°18′39″W / 37.2503°N 93.3107°W / 37.2503; -93.3107 (Springfield, Missouri diverging diamond interchange)). Construction began the week of January 12, 2009, and the interchange opened on June 21, 2009.[10][11] This interchange was a conversion of an existing standard diamond interchange, and used the existing bridge.

The first interchange in Canada opened on August 13, 2017 at Macleod Trail and 162 Avenue South in Calgary, Alberta.[12]

The interchange in Seclin (at 50°32′41″N 3°3′21″E / 50.54472°N 3.05583°E / 50.54472; 3.05583) between the A1 and Route d'Avelin was somewhat more specialized than in the diagram at right: eastbound traffic on Route d'Avelin intending to enter the A1 northbound must keep left and cross the northernmost bridge before turning left to proceed north onto A1; eastbound traffic continuing east on Route d'Avelin must select a single center lane, merge with A1 traffic that is exiting to proceed east, and cross a center bridge. All westbound traffic that is continuing west or turning south onto A1 uses the southernmost bridge.

Additional research was conducted by a partnership of the Virginia Polytechnic Institute and State University and the Turner-Fairbank Highway Research Center and published by Ohio Section of the Institute of Transportation Engineers.[13] The Federal Highway Administration released a publication titled "Alternative Intersections/Interchanges: Informational Report (AIIR)" [14] with a chapter dedicated to this design.

As of January 19, 2018, 106 DDIs were operational across the world including:

3D computer generated DCMI DCMI traffic flow patterns

A free-flowing interchange variant, patented in 2015,[21] has received recent attention.[22][23][24] Called the double crossover merging interchange (DCMI), it includes elements from the diverging diamond interchange, the tight diamond interchange, and the stack interchange. It eliminates the disadvantages of weaving and of merging into the outside lane from which the standard DDI variation suffers. As of 2016, no such interchanges have been constructed.

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For other uses, see Asphalt (disambiguation). Note: The terms bitumen and asphalt are mostly interchangeable, Asphalt Surfacing Contractors in Southgate except where asphalt is used as a shorthand for asphalt concrete. Natural bitumen from the Dead Sea Refined asphalt The University of Queensland pitch drop experiment, demonstrating the viscosity of asphalt

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Asphalt (/ˈæsˌfɔːlt, -ˌfɑːlt/), also known as bitumen (UK English: /ˈbɪtʃəmən, ˈbɪtjʊmən/,[1] US English: /bɪˈt(j)uːmən, baɪˈt(j)uːmən/)[2] is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used.

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The primary use (70%) of asphalt Asphalt Driveway Sealing Companies is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.

The terms “asphalt” and “bitumen” are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, “asphalt” (or “asphalt cement”) is commonly used for a refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called “bitumen”, and geologists worldwide often prefer the term for the naturally occurring variety. Common colloquial usage often refers to various forms of asphalt as “tar”, as in the name of the La Brea Tar Pits.

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Naturally occurring asphalt is sometimes specified by the term “crude bitumen”. Asphalt Surfacing Contractors Its viscosity is similar to that of cold molasses[6][7] while the material obtained from the fractional distillation of crude oil boiling at 525 °C (977 °F) is sometimes referred to as “refined bitumen”. The Canadian province of Alberta has most of the world’s reserves of natural asphalt in the Athabasca oil sands, which cover 142,000 square kilometres (55,000 sq mi), an area larger than England.

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The word “asphalt” is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word meaning “asphalt/bitumen/pitch” which perhaps derives from ἀ-, “without” and σφάλλω (sfallō), “make fall”.  Largest Asphalt Companies the first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall.[11] From the Greek, the word passed into late Latin, and thence into French (asphalte) and English (“asphaltum” and “asphalt”). In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the “asphaltic concrete” used to pave roads.

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The expression “bitumen” originated in the Sanskrit words jatu, meaning “pitch”, and jatu-krit, meaning “pitch creating” or “pitch producing” (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally gwitu-men (pertaining to pitch), and by others, pixtumens (exuding or bubbling pitch), which was subsequently shortened to bitumen, thence passing via French into English. From the same root is derived the Anglo-Saxon word cwidu (mastix), the German word Kitt (cement or mastic) and the old Norse word kvada.

In British English, “bitumen” is used instead of “asphalt”. The word “asphalt” is instead used to refer to asphalt concrete, a mixture of construction aggregate and asphalt itself (also called “tarmac” in common parlance). Bitumen mixed with clay was usually called “asphaltum”,[13] but the term is less commonly used today.[citation needed]

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In Australian English, “bitumen” is often used as the generic term for road surfaces.

In American English, “asphalt” is equivalent to the British “bitumen”. However, “asphalt” is also commonly used as a shortened form of “asphalt concrete” (therefore equivalent to the British “asphalt” or “tarmac”).

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In Canadian English, the word “bitumen” is used to refer to the vast Canadian deposits of extremely heavy crude oil,[14] while “asphalt” is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as “dilbit” in the Canadian petroleum industry, while bitumen “upgraded” to synthetic crude oil is known as “syncrude”, and syncrude blended with bitumen is called “synbit”.[15]

“Bitumen” is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. “Bituminous rock” is a form of sandstone impregnated with bitumen. The tar sands of Alberta, Canada are a similar material.

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Neither of the terms “asphalt” or “bitumen” should be confused with tar or coal tars.[further explanation needed]

See also: Asphaltene

The components of asphalt include four main classes of compounds:

The naphthene aromatics and polar aromatics are typically the majority components. Most natural bitumens also contain organosulfur compounds, resulting in an overall sulfur content of up to 4%. Nickel and vanadium are found at <10 parts per million, as is typical of some petroleum.

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The substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase.[16] “It is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large”.

Asphalt may be confused with coal tar, which is a visually similar black, thermoplastic material produced by the destructive distillation of coal. During the early and mid-20th century, when town gas was produced, coal tar was a readily available byproduct and extensively used as the binder for road aggregates. The addition of coal tar to macadam roads led to the word “tarmac”, which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, asphalt has completely overtaken the use of coal tar in these applications. Other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. “Pitch” is another term sometimes informally used at times to refer to asphalt, as in Pitch Lake.

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Bituminous outcrop of the Puy de la Poix, Clermont-Ferrand, France

The majority of asphalt used commercially is obtained from petroleum.[18] Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.

Natural deposits of bitumen include lakes such as the Pitch Lake in Trinidad and Tobago and Lake Bermudez in Venezuela. Natural seeps occur in the La Brea Tar Pits and in the Dead Sea.

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Bitumen also occurs in unconsolidated sandstones known as “oil sands” in Alberta, Canada, and the similar “tar sands” in Utah, US. The Canadian province of Alberta has most of the world’s reserves, in three huge deposits covering 142,000 square kilometres (55,000 sq mi), an area larger than England or New York state. These bituminous sands contain 166 billion barrels (26.4×10^9 m3) of commercially established oil reserves, giving Canada the third largest oil reserves in the world. Although historically it was used without refining to pave roads, nearly all of the output is now used as raw material for oil refineries in Canada and the United States.

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The world’s largest deposit of natural bitumen, known as the Athabasca oil sands, is located in the McMurray Formation of Northern Alberta. This formation is from the early Cretaceous, and is composed of numerous lenses of oil-bearing sand with up to 20% oil.[19] Isotopic studies show the oil deposits to be about 110 million years old.[20] Two smaller but still very large formations occur in the Peace River oil sands and the Cold Lake oil sands, to the west and southeast of the Athabasca oil sands, respectively. Of the Alberta deposits, only parts of the Athabasca oil sands are shallow enough to be suitable for surface mining. The other 80% has to be produced by oil wells using enhanced oil recovery techniques like steam-assisted gravity drainage.

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Much smaller heavy oil or bitumen deposits also occur in the Uinta Basin in Utah, US. The Tar Sand Triangle deposit, for example, is roughly 6% bitumen.

Bitumen may occur in hydrothermal veins. An example of this is within the Uinta Basin of Utah, in the US, where there is a swarm of laterally and vertically extensive veins composed of a solid hydrocarbon termed Gilsonite. These veins formed by the polymerization and solidification of hydrocarbons that were mobilized from the deeper oil shales of the Green River Formation during burial and diagenesis.

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Bitumen is similar to the organic matter in carbonaceous meteorites.[23] However, detailed studies have shown these materials to be distinct.[24] The vast Alberta bitumen resources are considered to have started out as living material from marine plants and animals, mainly algae, that died millions of years ago when an ancient ocean covered Alberta. They were covered by mud, buried deeply over time, and gently cooked into oil by geothermal heat at a temperature of 50 to 150 °C (120 to 300 °F). Due to pressure from the rising of the Rocky Mountains in southwestern Alberta, 80 to 55 million years ago, the oil was driven northeast hundreds of kilometres and trapped into underground sand deposits left behind by ancient river beds and ocean beaches, thus forming the oil sands.

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The use of natural bitumen for waterproofing, and as an adhesive dates at least to the fifth millennium BC, with a crop storage basket discovered in Mehrgarh, of the Indus Valley Civilization, lined with it.[25] By the 3rd millennia BC refined rock asphalt was in use, in the region, and was used to waterproof the Great Bath, Mohenjo-daro.

In the ancient Middle East, the Sumerians used natural bitumen deposits for mortar between bricks and stones, to cement parts of carvings, such as eyes, into place, for ship caulking, and for waterproofing.[3] The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon.

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The 1 kilometre (0.62 mi) long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis (ca. 800 BC) was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent.

Bitumen was used by ancient Egyptians to embalm mummies.[3][28] The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians’ primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake).

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Approximately 40 AD, Dioscorides described the Dead Sea material as Judaicum bitumen, and noted other places in the region where it could be found.[29] The Sidon bitumen is thought to refer to material found at Hasbeya.[30] Pliny refers also to bitumen being found in Epirus. It was a valuable strategic resource, the object of the first known battle for a hydrocarbon deposit—between the Seleucids and the Nabateans in 312 BC.

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In the ancient Far East, natural bitumen was slowly boiled to get rid of the higher fractions, leaving a thermoplastic material of higher molecular weight that when layered on objects became quite hard upon cooling. This was used to cover objects that needed waterproofing,[3] such as scabbards and other items. Statuettes of household deities were also cast with this type of material in Japan, and probably also in China.

In North America, archaeological recovery has indicated bitumen was sometimes used to adhere stone projectile points to wooden shafts.[32] In Canada, aboriginal people used bitumen seeping out of the banks of the Athabasca and other rivers to waterproof birch bark canoes, and also heated it in smudge pots to ward off mosquitoes in the summer.

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In 1553, Pierre Belon described in his work Observations that pissasphalto, a mixture of pitch and bitumen, was used in the Republic of Ragusa (now Dubrovnik, Croatia) for tarring of ships.

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An 1838 edition of Mechanics Magazine cites an early use of asphalt in France. A pamphlet dated 1621, by “a certain Monsieur d’Eyrinys, states that he had discovered the existence (of asphaltum) in large quantities in the vicinity of Neufchatel”, and that he proposed to use it in a variety of ways – “principally in the construction of air-proof granaries, and in protecting, by means of the arches, the water-courses in the city of Paris from the intrusion of dirt and filth”, which at that time made the water unusable. “He expatiates also on the excellence of this material for forming level and durable terraces” in palaces, “the notion of forming such terraces in the streets not one likely to cross the brain of a Parisian of that generation”.

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But the substance was generally neglected in France until the revolution of 1830. In the 1830s there was a surge of interest, and asphalt became widely used “for pavements, flat roofs, and the lining of cisterns, and in England, some use of it had been made of it for similar purposes”. Its rise in Europe was “a sudden phenomenon”, after natural deposits were found “in France at Osbann (Bas-Rhin), the Parc (Ain) and the Puy-de-la-Poix (Puy-de-Dôme)”, although it could also be made artificially.[35] One of the earliest uses in France was the laying of about 24,000 square yards of Seyssel asphalt at the Place de la Concorde in 1835.

Among the earlier uses of bitumen in the United Kingdom was for etching. William Salmon’s Polygraphice (1673) provides a recipe for varnish used in etching, consisting of three ounces of virgin wax, two ounces of mastic, and one ounce of asphaltum.[37] By the fifth edition in 1685, he had included more asphaltum recipes from other sources.

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The first British patent for the use of asphalt was “Cassell’s patent asphalte or bitumen” in 1834.[35] Then on 25 November 1837, Richard Tappin Claridge patented the use of Seyssel asphalt (patent #7849), for use in asphalte pavement,[39][40] having seen it employed in France and Belgium when visiting with Frederick Walter Simms, who worked with him on the introduction of asphalt to Britain.[41][42] Dr T. Lamb Phipson writes that his father, Samuel Ryland Phipson, a friend of Claridge, was also “instrumental in introducing the asphalte pavement (in 1836)”.[43] Indeed, mastic pavements had been previously employed at Vauxhall by a competitor of Claridge, but without success.

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Claridge obtained a patent in Scotland on 27 March 1838, and obtained a patent in Ireland on 23 April 1838. In 1851, extensions for the 1837 patent and for both 1838 patents were sought by the trustees of a company previously formed by Claridge. Claridge’s Patent Asphalte Company—formed in 1838 for the purpose of introducing to Britain “Asphalte in its natural state from the mine at Pyrimont Seysell in France”,—”laid one of the first asphalt pavements in Whitehall”.  Trials were made of the pavement in 1838 on the footway in Whitehall, the stable at Knightsbridge Barracks,”and subsequently on the space at the bottom of the steps leading from Waterloo Place to St. James Park”. “The formation in 1838 of Claridge’s Patent Asphalte Company (with a distinguished list of aristocratic patrons, and Marc and Isambard Brunel as, respectively, a trustee and consulting engineer), gave an enormous impetus to the development of a British asphalt industry”.[45] “By the end of 1838, at least two other companies, Robinson’s and the Bastenne company, were in production”,[50] with asphalt being laid as paving at Brighton, Herne Bay, Canterbury, Kensington, the Strand, and a large floor area in Bunhill-row, while meantime Claridge’s Whitehall paving “continue(d) in good order”.

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Asphalt Driveway Paving Price An alley in Fira, Santorini, Greece Sana'a, Yemen Howey Place, Melbourne, Australia Hagay Street, Old City, Jerusalem Rua Sobre-o-Douro, Porto, Portugal Peg Washington's Lane, Graiguenamanagh, County Kilkenny, Ireland

An alley or alleyway is a narrow lane, path, or passageway, often reserved for pedestrians, which usually runs between, behind, or within buildings in the older parts of towns and cities. It is also a rear access or service road (back lane), or a path or walk in a park or garden.[1]

A covered alley or passageway, often with shops, may be called an arcade. The origin of the word alley is late Middle English, from Old French: alee "walking or passage", from aler "go", from Latin: ambulare "to walk".[2]

The word alley is used in two main ways:

Grand Bazaar, Istanbul

In older cities and towns in Europe, alleys are often what is left of a medieval street network, or a right of way or ancient footpath. Similar paths also exist in some older North American towns and cities. In some older urban development in North America lanes at the rear of houses, to allow for deliveries and garbage collection, are called alleys. Alleys and ginnels were also the product of the 1875 Public Health Act in the United Kingdom, where usually alleys run along the back of streets of terraced houses, with ginnels connecting them to the street every fifth house.[citation needed] Alleys may be paved, or unpaved, and a blind alley is a cul-de-sac. Modern urban developments may also provide a service road to allow for waste collection, or rear access for fire engines and parking.

Because of geography, steps (stairs) are the predominant form of alley in hilly cities and towns. This includes Pittsburgh (see Steps of Pittsburgh), Cincinnati (see Steps of Cincinnati), Minneapolis, Seattle,[3] and San Francisco[4] in the United States, as well as Hong Kong,[5] Genoa and Rome.[6]

Some alleys are roofed because they are within buildings, such as the traboules of Lyon, or when they are a pedestrian passage through railway embankments in Britain. The latter follow the line of rights-of way that existed before the railway was built.

Arcades are another kind of covered passageway and the simplest kind are no more than alleys to which a glass roof was added later, like, for example, Howey Place, Melbourne, Australia (see also Block Place, Melbourne). However, most arcades differ from alleys in that they are architectural structures built with a commercial purpose and are a form of shopping mall. All the same alleys have for long been associated with various types of businesses, especially pubs and coffee houses. Bazaars and Souqs are an early form of arcade found in Asia and North Africa.

Some attractive historic alleys are found in older American and Canadian cities, like New York City, Philadelphia, Charleston, South Carolina, Boston, Annapolis, New Castle, Delaware, Quebec City, St John's, Newfoundland,[7] and Victoria, British Columbia.

View into Fan Tan Alley, Victoria, British Columbia, Canada

Québec City was originally built on the riverside bluff Cap Diamant in the 17th century, and throughout Quebec City there are strategically placed public stairways that link the bluff to the lower parts of the city.[8] The Upper City is the site of Old Québec’s most significant historical sites, including 17th- and 18th-century chapels, the Citadel and the city ramparts.

Fan Tan Alley is an alley in Victoria, British Columbia's Chinatown. It was originally a gambling district with restaurants, shops, and opium dens. Today it is a tourist destination with many small shops including a barber shop, art gallery, Chinese cafe and apartments. It may well be the narrowest street in Canada. At its narrowest point it is only 0.9 metres (35 in) wide.[9] Waddington Alley is another interesting alley in Victoria and the only street in that city still paved with wood blocks, an early pavement common in the downtown core. Other heritage features are buildings more than a century old lining the alley and a rare metal carriage curb that edges the sidewalk on the southern end.[10]

Looking south down Shubert Alley in Manhattan's Theater District

In the United States alleys exist in both older commercial and residential areas, for both service purposes and automobile access. In residential areas, particularly in those that were built before 1950, alleys provide rear access to property where a garage was located, or where waste could be collected by service vehicles. A benefit of this was the location of these activities to the rear, less public side of a dwelling. Such alleys are generally roughly paved, but some may be dirt. Beginning in the late 20th century, they were seldom included in plans for new housing developments.

When Annapolis, Maryland, was established as a city at the beginning of the 18th century,[11] the streets were established in circles. That encouraged the creation of shortcuts, which over time became paved alleys. Some ten of these survive, and the city has recently worked on making them more attractive.[12]

Several residential neighborhoods in Austin, Texas, have comprehensive alley systems. These include Hyde Park, Rosedale, and areas northwest of the Austin State Hospital.

In the Beacon Hill district of Boston, Massachusetts, Acorn Street, a narrow cobbled lane with row houses, is one of Boston's more attractive and historic alleys. Another early settled American city, New Castle, Delaware has a number of interesting alleys, some of which are footpaths and others narrow, sometimes cobbled, lanes open to traffic. Many of the alleys in the Back Bay and South End area are numbered (e.g. "Public Alley 438").

In the French Quarter of Charleston’s historic district, Philadelphia Alley (c. 1766), originally named "Cow Alley", is one of several picturesque alleys. In 1810 William Johnson gave it the name of "Philadelphia Alley", although locals call the "elegantly landscaped thoroughfare" "Dueler’s Alley".[13] Starting on East Bay Street, Stolls Alley is just seventeen bricks wide at its start, and named for Justinus Stoll, an 18th-century blacksmith.[14] For three hundred years, another of Charleston's narrow lanes, Lodge Alley, served a commercial purpose. Originally French Hugenot merchants built homes on it, along with warehouses to store supplies their ships. Just ten-foot-wide this alley was a useful means of access to Charleston’s waterways.[15] Today it leads to East Bay Street's many restaurants.

Main article: Steps of Cincinnati

Cincinnati is a city of hills.[16] Before the advent of the automobile a system of stairway alleys provided pedestrians important and convenient access to and from their hill top homes. At the height of their use in the 19th century, over 30 miles (48 km) of hill side steps once connected the neighborhoods of Cincinnati to each other.[17] The first steps were installed by residents of Mount Auburn in the 1830s in order to gain easier access to Findlay Market in Over-the-Rhine.[18] In recent years many steps have fallen into disrepair but there is a movement now to rehabilitate them.[19]

Broadway Alley is a rare alley in Manhattan; it is not located near Broadway, East Broadway or West Broadway

New York City's Manhattan is unusual in that it has very few alleys, since the Commissioner's Plan of 1811 did not include rear service alleys when it created Manhattan's grid. The exclusion of alleys has been criticized as a flaw in the plan, since services such as garbage pickup cannot be provided out of sight of the public, although other commentators feel that the lack of alleys is a benefit to the quality of life of the city.[20]

Two notable alleys in the Greenwich Village neighborhood in Manhattan are MacDougal Alley and Washington Mews.[21] The latter is a blind alley or cul-de-sac. Greenwich Village also has a number of private alleys that lead to back houses, which can only be accessed by residents, including Grove Court,[22] Patchin Place and Milligan Place, blind alleys. Patchin Place is notable for the writers who lived there.[23]

Shubert Alley is a 300-foot (91 m) long pedestrian alley at the heart of the Broadway theater district of New York City. The alley was originally created as a fire exit between the Shubert Theatre on West 45th Street and the Booth Theatre on West 44th Street, and the Astor Hotel to their east. Actors once gathered in the alley, hoping to attract the attention of the Shubert Brothers and get employment in their theatrical productions.[24] When the hotel was torn down, and replaced with One Astor Plaza (1515 Broadway), the apparent width of the alley increased, as the new building did not go all the way to the westernmost edge of the building lot. However, official, Shubert Alley consists only of the space between the two theatres and the lot line.

In the Brooklyn Heights neighborhood of Brooklyn, Grace Court Alley is another converted mews,[25] as is Dennett Place in the Carroll Gardens neighborhood.[26] The former is a cul-de-sac.

Pedestrians walking along Elfreth's Alley, Philadelphia

The Old City and Society Hill neighborhoods of Philadelphia, the oldest parts of the city, include a number of alleys, notably Elfreth's Alley, which is called "Our nation's oldest residential street", dating from 1702.[27] As of 2012[update], there were 32 houses on the street, which were built between 1728 and 1836.[28]

There are numerous cobblestoned residential passages in Philadelphia, many no wider than a truck, and typically flanked with brick houses. A typical house on these alleys or lanes is called a Philadelphia "Trinity", named because it has three rooms, one to each floor, alluding to the Christian Trinity.[29] These alleys include Willings Alley, between S. 3rd and S. 4th Streets and Walnut and Spruce Streets.[30] Other streets in Philadelphia which fit the general description of an alley, but are not named "alley", include Cuthbert Street, Filbert Street, Phillips Street,[31] South American Street,[32] Sansom Walk,[33] St. James Place,[34] and numerous others.

Steps, Pittsburgh's equivalent for an alley, have defined it for many visitors. Writing in 1937, war correspondent Ernie Pyle wrote of the steps of Pittsburgh:

And then the steps. Oh Lord, the steps! I was told they actually had a Department of Steps. That isn’t exactly true, although they do have an Inspector of Steps. But there are nearly 15 miles (24 km) of city-owned steps, going up mountainsides.[35]

The City of Pittsburgh maintains 712 sets of city-owned steps, some of which are shown as streets on maps.[36]

In hilly San Francisco, California alleys often take the form of steps and it has several hundred public stairways.[37] Among the most famous is the stairway known as the Filbert steps, a continuation of Filbert Street.[38] The Filbert Street Steps descend the east slope of Telegraph Hill along the line where Filbert Street would be if the hill was not so steep. The stairway is bordered by greenery, that consists both backyards, and a border garden tended to and paid for by the residents of the "street", and runs down to an eastern stub of Filbert Street and the walkway through the plaza to The Embarcadero. Many houses in this residential neighborhood are accessible only from the steps.

Also in San Francisco, Belden Place is a narrow pedestrian alley, bordered by restaurants, in the Financial District, referred to as San Francisco's French Quarter for its historic ties to early French immigrants, and its popular contemporary French restaurants and institutions.[39] The area was home to San Francisco's first French settlers. Approximately 3,000, sponsored by the French government, arrived near the end of the Gold Rush in 1851.[40]

Alley in Sausalito, California

Seattle is a city of hills, bluffs, and canyons and many stairs. There are over 600 publicly accessible Seattle stairways within the city limits.[41]

Ruelle verte (Green alley) Montréal, Québec, Canada.

Numerous cities in the United States and Canada, such as Chicago,[42] Seattle,[43] Los Angeles,[44] Phoenix, Washington, D.C.,[45] and Montréal, have started reclaiming their alleys from garbage and crime by greening the service lanes, or back ways, that run behind some houses.[45][46] Chicago, Illinois has about 1,900 miles (3,100 km) of alleyways.[42] In 2007, the Chicago Department of Transportation started converting conventional alleys which were paved with asphalt into so called Green Alleys. This program, called the Green Alley Program, is supposed to enable easier water runoff, as the alleyways in Chicago are not connected directly to the sewer system. With this program, the water will be able to seep through semi-permeable concrete or asphalt in which a colony of fungi and bacteria will establish itself. The bacteria will help breakup oils before the water is absorbed into the ground. The lighter color of the pavement will also reflect more light, making the area next to the alley cooler.[47] The greening of such alleys or laneways can also involve the planting of native plants to further absorb rain water and moderate temperature.

New life has also come to other alleys within downtown commercial districts of various cities throughout the world with the opening of businesses, such as coffee houses, shops, restaurants and bars.

Another way that alleys and laneways are being revitalized is through laneway housing. A laneway house is a form of housing that has been proposed on the west coast of Canada, especially in the Metro Vancouver area. These homes are typically built into pre-existing lots, usually in the backyard and opening onto the back lane. This form of housing already exists in Vancouver, and revised regulations now encourage new developments as part of a plan to increase urban density in pre-existing neighbourhoods while retaining a single-family feel to the area.[48] Vancouver's average laneway house is one and a half stories, with one or two bedrooms. Typical regulations require that the laneway home is built on the back half of a traditional lot in the space normally reserved for a garage.[49][50]

Toronto also has a tradition of laneway housing and changed regulations to encourage new development.[51] However this was discontinued in 2006 after staff reviewed the impact on services and safety.[52]

London has numerous historical alleys, especially, but not exclusively, in its centre; this includes The City, Covent Garden, Holborn, Clerkenwell, Westminster and Bloomsbury amongst others.

An alley in London can also be called a passage, court, place, lane, and less commonly path, arcade, walk, steps, yard, terrace, and close.[53] While both a court and close are usually defined as blind alleys, or cul-de-sacs, several in London are throughways, for example Cavendish Court, a narrow passage leading from Houndsditch into Devonshire Square, and Angel Court, which links King Street and Pall Mall.[54] Bartholomew Close is a narrow winding lane which can be called an alley by virtue of its narrowness, and because through-access requires the use of passages and courts between Little Britain, and Long Lane and Aldersgate Street.[55]

In an old neighbourhood of the City of London, Exchange Alley or Change Alley is a narrow alleyway connecting shops and coffeehouses.[56] It served as a convenient shortcut from the Royal Exchange on Cornhill to the Post Office on Lombard Street and remains as one of a number of alleys linking the two streets. The coffeehouses[57] of Exchange Alley, especially Jonathan's and Garraway's, became an early venue for the lively trading of shares and commodities. These activities were the progenitor of the modern London Stock Exchange.

Boundary Passage, Shoreditch, London, England

Lombard Street and Change Alley had been the open-air meeting place of London's mercantile community before Thomas Gresham founded the Royal Exchange in 1565.[58] In 1698, John Castaing began publishing the prices of stocks and commodities in Jonathan's Coffeehouse, providing the first evidence of systematic exchange of securities in London.

Change Alley was the site of some noteworthy events in England's financial history, including the South Sea Bubble from 1711 to 1720 and the panic of 1745.[59]

In 1761 a club of 150 brokers and jobbers was formed to trade stocks. The club built its own building in nearby Sweeting's Alley in 1773, dubbed the "New Jonathan's", later renamed the Stock Exchange.[60]

West of the City there are a number of alleys just north of Trafalgar Square, including Brydges Place which is situated right next to the Coliseum Theatre and just 15 inches wide at its narrowest point, only one person can walk down it at a time. It is the narrowest alley in London and runs for 200 yards (180 m), connecting St Martin's Lane with Bedfordbury in Covent Garden.[61]

Close by is another very narrow passage, Lazenby Court, which runs from Rose Street to Floral Street down the side of the Lamb and Flag pub; in order to pass people must turn slightly sideways. The Lamb & Flag in Rose Street has a reputation as the oldest pub in the area,[62] though records are not clear. The first mention of a pub on the site is 1772.[63] The Lazenby Court was the scene of an attack on the famous poet and playwright John Dryden in 1679 by thugs hired by John Wilmot, 2nd Earl of Rochester,[64] with whom he had a long-standing conflict.[65]

In the same neighbourhood Cecil Court has an entirely different character than the two previous alleys, and is a spacious pedestrian street with Victorian shop-frontages that links Charing Cross Road with St. Martin's Lane, and it is sometimes used as a location by film companies.[66][67]

One of the older thoroughfares in Covent Garden, Cecil Court dates back to the end of the 17th century. A tradesman's route at its inception, it later acquired the nickname Flicker Alley because of the concentration of early film companies in the Court.[68] The first film-related company arrived in Cecil Court in 1897, a year after the first demonstration of moving pictures in the United Kingdom and a decade before London’s first purpose built cinema opened its doors. Since the 1930s it has been known as the new Booksellers' Row as it is home to nearly twenty antiquarian and second-hand independent bookshops.

It was the temporary home of an eight-year-old Wolfgang Amadeus Mozart while he was touring Europe in 1764. For almost four months the Mozart family lodged with barber John Couzin.[69] According to some modern authorities, Mozart composed his first symphony while a resident of Cecil Court.[70]

North of the centre of London, Camden Passage is a pedestrian passage off Upper Street in the London Borough of Islington, famous because of its many antiques shops, and an antique market on Wednesdays and Saturday mornings. It was built, as an alley, along the backs of houses on Upper Street, then Islington High Street, in 1767.[71]

An alley (usually called a ginnel) in Moss Side, Manchester Tolbooth Wynd, Edinburgh

In Scotland and Northern Ireland the Scots terms close, wynd, pend and vennel are general in most towns and cities. The term close has an unvoiced "s" as in sad. The Scottish author Ian Rankin's novel Fleshmarket Close was retitled Fleshmarket Alley for the American market. Close is the generic Scots term for alleyways, although they may be individually named closes, entries, courts and wynds. A close was private property, hence gated and closed to the public.

A wynd is typically a narrow lane between houses, an open throughway, usually wide enough for a horse and cart. The word derives from Old Norse venda, implying a turning off a main street, without implying that it is curved.[87] In fact, most wynds are straight. In many places wynds link streets at different heights and thus are mostly thought of as being ways up or down hills.

A pend is a passageway that passes through a building, often from a street through to a courtyard, and typically designed for vehicular rather than exclusively pedestrian access.[88] A pend is distinct from a vennel or a close, as it has rooms directly above it, whereas vennels and closes are not covered over.

A vennel is a passageway between the gables of two buildings which can in effect be a minor street in Scotland and the north east of England, particularly in the old centre of Durham. In Scotland, the term originated in royal burghs created in the twelfth century, the word deriving from the Old French word venelle meaning "alley" or "lane". Unlike a tenement entry to private property, known as a "close", a vennel was a public way leading from a typical high street to the open ground beyond the burgage plots.[89] The Latin form is venella.

Traboule, Vieux Lyon, France

The traboules of Lyon are passageways that cut through a house or, in some cases, a whole city block, linking one street with another. They are distinct from most other alleys in that they are mainly enclosed within buildings and may include staircases. While they are found in other French cities including Villefranche-sur-Saône, Mâcon, Chambéry, Saint-Étienne, Louhans, Chalon sur Saône and Vienne (Isère), Lyon has many more; in all there are about 500. The word traboule comes from the Latin trans ambulare, meaning "to cross", and the first of them were possibly built as early as the 4th century. As the Roman Empire disintegrated, the residents of early Lyon—Lugdunum, the capital of Roman Gaul—were forced to move from the Fourvière hill to the banks of the river Saône when their aqueducts began to fail. The traboules grew up alongside their new homes, linking the streets that run parallel to the river Saône and going down to the river itself. For centuries they were used by people to fetch water from the river and then by craftsmen and traders to transport their goods. By the 18th century they were invaluable to what had become the city’s defining industry, textiles, especially silk.[97] Nowadays, traboules are tourist attractions, and many are free and open to the public. Most traboules are on private property, serving as entrances to local apartments.

Venice is largely a traffic free city and there is, in addition to the canals, a maze of around 3000 lanes and alleys called calli (which means narrow). Smaller ones are callètte or callesèlle, while larger ones are calli large. Their width varies from just over 50 centimetres (19.7 in) to 5–6 metres (196.9–236.2 in). The narrowest is Calletta Varisco, which just 53 centimetres (20.9 in); Calle Stretta is 65 centimetres (25.6 in) wide and Calle Ca’ Zusto 68 centimetres (26.8 in). The main ones are also called salizada and wider calli, where trade proliferates, are called riga', while blind calli, used only by residents to reach their homes, are ramo.[98]

Spreuerhofstraße is the world's narrowest street, found in the city of Reutlingen, Baden-Württemberg, Germany.[99] It ranges from 31 centimetres (12.2 in) at its narrowest to 50 centimetres (19.7 in) at its widest.[100] The lane was built in 1727 during the reconstruction efforts after the area was completely destroyed in the massive citywide fire of 1726 and is officially listed in the Land-Registry Office as City Street Number 77.[99][101]

Lintgasse is an alley (German: Gasse) in the Old town of Cologne, Germany between the two squares of Alter Markt and Fischmarkt. It is a pedestrian zone and though only some 130 metres long, is nevertheless famous for its medieval history. The Lintgasse was first mentioned in the 12th century as in Lintgazzin, which may be derived from basketmakers who wove fish baskets out of Linden tree barks. These craftsmen were called Lindslizer, meaning Linden splitter. During the Middle Ages, the area was also known as platēa subri or platēa suberis, meaning street of Quercus suber, the cork oak tree. Lintgasse 8 to 14 used to be homes of medieval knights as still can be seen by signs like Zum Huynen, Zum Ritter or Zum Gir. During the 19th-century the Lintgasse was called Stink-Linkgaß, a because of its poor air quality.[102]

A view of Spreuerhofstraße in Germany, showing the sign indicating that is the world's record narrowest street

Gränd is Swedish for an alley and there are numerous gränder, or alleys in Gamla stan, The Old Town, of Stockholm, Sweden. The town dates back to the 13th century, with medieval alleyways, cobbled streets, and historic buildings. North German architecture has had a strong influence in the Old Town's buildings. Some of Stockholm's alleys are very narrow pedestrian footpaths, while others are very narrow, cobbled streets, or lanes open to slow moving traffic. Mårten Trotzigs gränd ("Alley of Mårten Trotzig") runs from Västerlånggatan and Järntorget up to Prästgatan and Tyska Stallplan, and part of it consists of 36 steps. At its narrowest the alley is a mere 90 cm (35 inches) wide, making it the narrowest street in Stockholm.[103] The alley is named after the merchant and burgher Mårten Trotzig (1559–1617), who, born in Wittenberg,[103] emigrated to Stockholm in 1581, and bought properties in the alley in 1597 and 1599, also opening a shop there. According to sources from the late 16th century, he was dealing in first iron and later copper, by 1595 had sworn his burgher oath, and was later to become one of the richest merchants in Stockholm.[104]

Mårten Trotzigs Gränd, 90 cm wide, the narrowest alley in Gamla stan, Stockholm, Sweden

Possibly referred to as Trångsund ("Narrow strait") before Mårten Trotzig gave his name to the alley, it is mentioned in 1544 as Tronge trappe grenden ("Narrow Alley Stairs"). In 1608 it is referred to Trappegrenden ("The Stairs Alley"), but a map dated 1733 calls it Trotz gränd. Closed off in the mid 19th century, not to be reopened until 1945, its present name was officially sanctioned by the city in 1949.[104]

The "List of streets and squares in Gamla stan" provides links to many pages that describe other alleys in the oldest part of Stockholm; e.g. Kolmätargränd (Coal Meter's Alley); Skeppar Karls Gränd (Skipper Karl's Alley); Skeppar Olofs Gränd (Skipper Olof's Alley); and Helga Lekamens Gränd (Alley of the Holy Body).

A hutong in Beijing

Hutongs (simplified Chinese: 胡同; traditional Chinese: 衚衕; pinyin: hútòng; Wade–Giles: hu-t'ung) are a type of narrow streets or alleys, commonly associated with northern Chinese cities, most prominently Beijing.

In Beijing, hutongs are alleys formed by lines of siheyuan, traditional courtyard residences.[105] Many neighbourhoods were formed by joining one siheyuan to another to form a hutong, and then joining one hutong to another. The word hutong is also used to refer to such neighbourhoods. During China’s dynastic period, emperors planned the city of Beijing and arranged the residential areas according to the social classes of the Zhou Dynasty (1027 – 256 BC). The term "hutong" appeared first during the Yuan Dynasty, and is a term of Mongolian origin meaning "town".[106]

At the turn of the 20th century, the Qing court was disintegrating as China’s dynastic era came to an end. The traditional arrangement of hutongs was also affected. Many new hutongs, built haphazardly and with no apparent plan, began to appear on the outskirts of the old city, while the old ones lost their former neat appearance.

Following the founding of the People’s Republic of China in 1949, many of the old hutongs of Beijing disappeared, replaced by wide boulevards and high rises. Many residents left the lanes where their families lived for generations for apartment buildings with modern amenities. In Xicheng District, for example, nearly 200 hutongs out of the 820 it held in 1949 have disappeared. However, many of Beijing’s ancient hutongs still stand, and a number of them have been designated protected areas. Many hutongs, some several hundred years old, in the vicinity of the Bell Tower and Drum Tower and Shichahai Lake are preserved amongst recreated contemporary two- and three-storey versions.[107][108]

A longtang in Shangxian Fang, a residential compound in Shanghai, China.

Hutongs represent an important cultural element of the city of Beijing and the hutongs are residential neighborhoods which still form the heart of Old Beijing. While most Beijing hutongs are straight, Jiudaowan (九道弯, literally "Nine Turns") Hutong turns nineteen times. At its narrowest section, Qianshi Hutong near Qianmen (Front Gate) is only 40 centimeters (16 inches) wide.[109]

The Shanghai longtang is loosely equivalent to the hutong of Beijing. A longtang (弄堂 lòngtáng, Shanghainese: longdang) is a laneway in Shanghai and, by extension, a community centred on a laneway or several interconnected laneways. On its own long (traditional Chinese 衖 or 弄, simplified Chinese 弄) is a Chinese term for "alley" or "lane", which is often left untranslated in Chinese addresses, but may also be translated as "lane", and "tang" is a parlor or hallway.[110] It is sometimes called lilong (里弄); the latter name incorporates the -li suffix often used in the name of residential developments in the late 19th and early 20th centuries. As with the term hutong, the Shanghai longdang can either refers to the lanes that the houses face onto, or a group of houses connected by the lane.[111][112][113][114]

A Golden Gai alley, Tokyo, Japan.

Shinjuku Golden Gai (新宿ゴールデン街) is a small area of Shinjuku, Tokyo, Japan,[115] famous both as an area of architectural interest and for its nightlife. It is composed of a network of six narrow alleys, connected by even narrower passageways which are just about wide enough for a single person to pass through. Over 200 tiny shanty-style bars, clubs and eateries are squeezed into this area.[116]

Its architectural importance is that it provides a view into the relatively recent past of Tokyo, when large parts of the city resembled present-day Golden Gai, particularly in terms of the extremely narrow lanes and the tiny two-storey buildings. Nowadays, most of the surrounding area has been redeveloped. Typically, the buildings are just a few feet wide and are built so close to the ones next door that they nearly touch. Most are two-storey, having a small bar at street level and either another bar or a tiny flat upstairs, reached by a steep set of stairs. None of the bars are very large; some are so small that they can only fit five or so customers at one time.[115] The buildings are generally ramshackle, and the alleys are dimly lit, giving the area a very scruffy and run-down appearance. However, Golden Gai is not a cheap place to drink, and the clientele that it attracts is generally well off.

Golden Gai is well known as a meeting place for musicians, artists, directors, writers, academics and actors, including many celebrities. Many of the bars only welcome regular customers, who initially should be introduced by an existing patron, although many others welcome non-regulars, some even making efforts to attract overseas tourists by displaying signs and price lists in English.[115]

Golden Gai was known for prostitution before 1958, when prostitution became illegal. Since then it has developed as a drinking area, and at least some of the bars can trace their origins back to the 1960s.[116]

A medina quarter (Arabic: المدينة القديمةal-madīnah al-qadīmah "the old city") is a distinct city section found in many North African cities. The medina is typically walled, contains many narrow and maze-like streets.[117] The word "medina" (Arabic: مدينةmadīnah) itself simply means "city" or "town" in modern Arabic.

Because of the very narrow streets, medinas are generally free from car traffic, and in some cases even motorcycle and bicycle traffic. The streets can be less than a metre wide. This makes them unique among highly populated urban centres. The Medina of Fes, Morocco or Fes el Bali, is considered one of the largest car-free urban areas in the world.[118]

Notes

Bibliography


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Asphalt Contractors Near Me Moderate to severe Fatigue cracking.

Crocodile cracking, also called alligator cracking and perhaps misleadingly fatigue cracking, is a common type of distress in asphalt pavement. The following is more closely related to fatigue cracking which is characterized by interconnecting or interlaced cracking in the asphalt layer resembling the hide of a crocodile.[1] Cell sizes can vary in size up to 11.80 inches (300 mm) across, but are typically less than 5.90 inches (150 mm) across. Fatigue cracking is generally a loading failure,[1] but numerous factors can contribute to it. It is often a sign of sub-base failure, poor drainage, or repeated over-loadings. It is important to prevent fatigue cracking, and repair as soon as possible, as advanced cases can be very costly to repair and can lead to formation of potholes or premature pavement failure.

It is usually studied under the transportation section of civil engineering.

Fatigue cracking is an asphalt pavement distress most often instigated by failure of the surface due to traffic loading. However, fatigue cracking can be greatly influenced by environmental and other effects while traffic loading remains the direct cause. Frequently, overloading happens because the base or subbase inadequately support the surface layer and subsequently cannot handle loads that it would normally endure.[2] There are many ways that the subbase or base can be weakened.

Poor drainage in the road bed is a frequent cause of this degradation of the base or subgrade.[1] A heavy spring thaw, similarly to poor drainage, can weaken the base course, leading to fatigue cracking.[1]

Stripping or raveling is another possible cause of fatigue cracking. Stripping occurs when poor adhesion between asphalt and aggregate allows the aggregate at the surface to dislodge. If left uncorrected, this reduces the thickness of the pavement, reducing the affected portion's ability to carry its designed loading.[1] This can cause fatigue cracking to develop rapidly, as overloading will happen with loads of less magnitude or frequency.

Edge cracking is the formation of crescent-shaped cracks near the edge of a road.[3] It is caused by lack of support of the road edge, sometimes due to poorly drained or weak shoulders. If left untreated, additional cracks will form until it resembles fatigue cracking.[3] Like wheel-path fatigue cracking, poor drainage is a main cause of edge cracking, as it weakens the base, which hastens the deterioration of the pavement.[4] Water ponding (a buildup of water which can also be called puddling) happens more frequently near the edge than in the center of the road path, as roads are usually sloped to prevent in-lane ponding. This leads to excess moisture in the shoulders and subbase at the road edge. Edge cracking differs from fatigue cracking in that the cracks form from the top down, where fatigue cracks usually start at the bottom and propagate to the surface.

Fatigue cracking manifests itself initially as longitudinal cracking (cracks along the direction of the flow of traffic) in the top layer of the asphalt.[5] These cracks are initially thin and sparsely distributed. If further deterioration is allowed, these longitudinal cracks are connected by transverse cracks to form sharp sided, prismatic pieces. This interlaced cracking pattern resembles the scales on the back of a crocodile or alligator, hence the nickname, crocodile cracking.

More severe cases involve pumping of fines, spalling, and loose pieces of pavement. The most severe cases of fatigue cracking often occur with other pavement distresses, but are exemplified by: potholes,[1] large cracks(3/8" or larger), and severely spalled edges.[4]

There are many different ways to measure fatigue cracking, but in general a pavement distress manual or index will be used. For example, the Pavement Condition Index is widely used to quantify the overall level of distress and condition of a section of road. Measurement of fatigue cracking specifically (and pavement distress in general) is necessary to determine the overall condition of a road, and for determination of a time-line for rehabilitation and/or repair. There are many other rating systems, and many rating systems currently in use are based on the AASHO Road Test.

There are two important criteria to take into account when measuring fatigue cracking. The first is the extent of the cracking. This is the amount of road surface area which is affected by this pavement distress. The second criterion is the severity of the cracking.[6] Severity, which has been discussed above, refers to how far the cracking has progressed, and is often directly a function of crack width.[6] Severity may be rated numerically, or given a rating from "low" to "severe". The rating may be entered into a pavement management system, which will suggest a priority and method for the repair.

Systems have been developed that detect fatigue cracking and other types of pavement distress automatically.[7] They measure the severity and frequency of alligator cracking on the road-path. One such machine is the road surface profilometer, which is mounted on a vehicle and measures the profile of the road surface while it is moving down the roadway.

Preventing fatigue cracking can be as simple as preventing the common causes. For example, reducing overloading on an asphalt pavement or improving drainage[2] can prevent fatigue cracking in many cases. Prevention primarily depends on designing and constructing the pavement and subbase to support the expected traffic loads, and providing good drainage to keep water out of the subbase.

A good strategy to prevent overloading, which is a main cause of fatigue cracking, is to increase the depth of the asphalt layer. According to certain researchers, pavements that exceed a certain minimum strength or thickness can hypothetically handle infinitely many loads without showing structural defects, including fatigue cracking.[1] These pavements are called perpetual pavements or long-term performance pavements (LTPP).

When repairing pavement affected by fatigue cracking, the main cause of the distress should be determined. However, often the specific cause is fairly difficult to determine, and prevention is therefore correspondingly difficult. Any investigation should involve digging a pit or coring the pavement and subbase to determine the pavement's structural makeup as well as determining whether or not subsurface moisture is a contributing factor.[1] The repair needed also differs based on the severity and extent of the cracking.

In the early stages, sealing cracks with crack sealant limits further deterioration of the subgrade due to moisture penetration. Small areas may be repaired by removal of the affected area, and replacement with new base and asphalt surface.[2] Once the damage has progressed or the affected area is large and extensive, a structural asphalt overlay or complete reconstruction is necessary to ensure structural integrity. Proper repair may include first sealing cracks with crack sealant, installing paving fabric over a tack coat, or milling the damaged asphalt. An overlay of hot mix asphalt is then placed over the completed repair. [2]

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Asphalt And Pavement Contractor Alberton

For other uses, see Asphalt (disambiguation). Note: The terms bitumen and asphalt are mostly interchangeable, Asphalt And Pavement Contractor in Alberton except where asphalt is used as a shorthand for asphalt concrete. Natural bitumen from the Dead Sea Refined asphalt The University of Queensland pitch drop experiment, demonstrating the viscosity of asphalt

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Asphalt (/ˈæsˌfɔːlt, -ˌfɑːlt/), also known as bitumen (UK English: /ˈbɪtʃəmən, ˈbɪtjʊmən/,[1] US English: /bɪˈt(j)uːmən, baɪˈt(j)uːmən/)[2] is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used.

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The primary use (70%) of asphalt Asphalt Driveway Extension Cost is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.

The terms “asphalt” and “bitumen” are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, “asphalt” (or “asphalt cement”) is commonly used for a refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called “bitumen”, and geologists worldwide often prefer the term for the naturally occurring variety. Common colloquial usage often refers to various forms of asphalt as “tar”, as in the name of the La Brea Tar Pits.

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Naturally occurring asphalt is sometimes specified by the term “crude bitumen”. Asphalt And Pavement Contractor Its viscosity is similar to that of cold molasses[6][7] while the material obtained from the fractional distillation of crude oil boiling at 525 °C (977 °F) is sometimes referred to as “refined bitumen”. The Canadian province of Alberta has most of the world’s reserves of natural asphalt in the Athabasca oil sands, which cover 142,000 square kilometres (55,000 sq mi), an area larger than England.

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The word “asphalt” is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word meaning “asphalt/bitumen/pitch” which perhaps derives from ἀ-, “without” and σφάλλω (sfallō), “make fall”.  Asphalt Companies Near Me the first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall.[11] From the Greek, the word passed into late Latin, and thence into French (asphalte) and English (“asphaltum” and “asphalt”). In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the “asphaltic concrete” used to pave roads.

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The expression “bitumen” originated in the Sanskrit words jatu, meaning “pitch”, and jatu-krit, meaning “pitch creating” or “pitch producing” (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally gwitu-men (pertaining to pitch), and by others, pixtumens (exuding or bubbling pitch), which was subsequently shortened to bitumen, thence passing via French into English. From the same root is derived the Anglo-Saxon word cwidu (mastix), the German word Kitt (cement or mastic) and the old Norse word kvada.

In British English, “bitumen” is used instead of “asphalt”. The word “asphalt” is instead used to refer to asphalt concrete, a mixture of construction aggregate and asphalt itself (also called “tarmac” in common parlance). Bitumen mixed with clay was usually called “asphaltum”,[13] but the term is less commonly used today.[citation needed]

Asphalt

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In Australian English, “bitumen” is often used as the generic term for road surfaces.

In American English, “asphalt” is equivalent to the British “bitumen”. However, “asphalt” is also commonly used as a shortened form of “asphalt concrete” (therefore equivalent to the British “asphalt” or “tarmac”).

Asphalt Repair Costs

In Canadian English, the word “bitumen” is used to refer to the vast Canadian deposits of extremely heavy crude oil,[14] while “asphalt” is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as “dilbit” in the Canadian petroleum industry, while bitumen “upgraded” to synthetic crude oil is known as “syncrude”, and syncrude blended with bitumen is called “synbit”.[15]

“Bitumen” is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. “Bituminous rock” is a form of sandstone impregnated with bitumen. The tar sands of Alberta, Canada are a similar material.

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Neither of the terms “asphalt” or “bitumen” should be confused with tar or coal tars.[further explanation needed]

See also: Asphaltene

The components of asphalt include four main classes of compounds:

The naphthene aromatics and polar aromatics are typically the majority components. Most natural bitumens also contain organosulfur compounds, resulting in an overall sulfur content of up to 4%. Nickel and vanadium are found at <10 parts per million, as is typical of some petroleum.

Tarmac Driveways Near Me

The substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase.[16] “It is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large”.

Asphalt may be confused with coal tar, which is a visually similar black, thermoplastic material produced by the destructive distillation of coal. During the early and mid-20th century, when town gas was produced, coal tar was a readily available byproduct and extensively used as the binder for road aggregates. The addition of coal tar to macadam roads led to the word “tarmac”, which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, asphalt has completely overtaken the use of coal tar in these applications. Other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. “Pitch” is another term sometimes informally used at times to refer to asphalt, as in Pitch Lake.

Asphalt Driveway Costs

Bituminous outcrop of the Puy de la Poix, Clermont-Ferrand, France

The majority of asphalt used commercially is obtained from petroleum.[18] Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.

Natural deposits of bitumen include lakes such as the Pitch Lake in Trinidad and Tobago and Lake Bermudez in Venezuela. Natural seeps occur in the La Brea Tar Pits and in the Dead Sea.

Residential Paving Cost Estimate

Bitumen also occurs in unconsolidated sandstones known as “oil sands” in Alberta, Canada, and the similar “tar sands” in Utah, US. The Canadian province of Alberta has most of the world’s reserves, in three huge deposits covering 142,000 square kilometres (55,000 sq mi), an area larger than England or New York state. These bituminous sands contain 166 billion barrels (26.4×10^9 m3) of commercially established oil reserves, giving Canada the third largest oil reserves in the world. Although historically it was used without refining to pave roads, nearly all of the output is now used as raw material for oil refineries in Canada and the United States.

Sidewalk

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The world’s largest deposit of natural bitumen, known as the Athabasca oil sands, is located in the McMurray Formation of Northern Alberta. This formation is from the early Cretaceous, and is composed of numerous lenses of oil-bearing sand with up to 20% oil.[19] Isotopic studies show the oil deposits to be about 110 million years old.[20] Two smaller but still very large formations occur in the Peace River oil sands and the Cold Lake oil sands, to the west and southeast of the Athabasca oil sands, respectively. Of the Alberta deposits, only parts of the Athabasca oil sands are shallow enough to be suitable for surface mining. The other 80% has to be produced by oil wells using enhanced oil recovery techniques like steam-assisted gravity drainage.

Paver Repair Cost Estimate

Much smaller heavy oil or bitumen deposits also occur in the Uinta Basin in Utah, US. The Tar Sand Triangle deposit, for example, is roughly 6% bitumen.

Bitumen may occur in hydrothermal veins. An example of this is within the Uinta Basin of Utah, in the US, where there is a swarm of laterally and vertically extensive veins composed of a solid hydrocarbon termed Gilsonite. These veins formed by the polymerization and solidification of hydrocarbons that were mobilized from the deeper oil shales of the Green River Formation during burial and diagenesis.

Pave My Driveway Price

Bitumen is similar to the organic matter in carbonaceous meteorites.[23] However, detailed studies have shown these materials to be distinct.[24] The vast Alberta bitumen resources are considered to have started out as living material from marine plants and animals, mainly algae, that died millions of years ago when an ancient ocean covered Alberta. They were covered by mud, buried deeply over time, and gently cooked into oil by geothermal heat at a temperature of 50 to 150 °C (120 to 300 °F). Due to pressure from the rising of the Rocky Mountains in southwestern Alberta, 80 to 55 million years ago, the oil was driven northeast hundreds of kilometres and trapped into underground sand deposits left behind by ancient river beds and ocean beaches, thus forming the oil sands.

Asphalt Installation Cost Estimate

The use of natural bitumen for waterproofing, and as an adhesive dates at least to the fifth millennium BC, with a crop storage basket discovered in Mehrgarh, of the Indus Valley Civilization, lined with it.[25] By the 3rd millennia BC refined rock asphalt was in use, in the region, and was used to waterproof the Great Bath, Mohenjo-daro.

In the ancient Middle East, the Sumerians used natural bitumen deposits for mortar between bricks and stones, to cement parts of carvings, such as eyes, into place, for ship caulking, and for waterproofing.[3] The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon.

Asphalt Driveway Price

The 1 kilometre (0.62 mi) long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis (ca. 800 BC) was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent.

Bitumen was used by ancient Egyptians to embalm mummies.[3][28] The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians’ primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake).

Driveway Pavers Cost Estimate

Approximately 40 AD, Dioscorides described the Dead Sea material as Judaicum bitumen, and noted other places in the region where it could be found.[29] The Sidon bitumen is thought to refer to material found at Hasbeya.[30] Pliny refers also to bitumen being found in Epirus. It was a valuable strategic resource, the object of the first known battle for a hydrocarbon deposit—between the Seleucids and the Nabateans in 312 BC.

Asphalt Surfacing Contractors Price

In the ancient Far East, natural bitumen was slowly boiled to get rid of the higher fractions, leaving a thermoplastic material of higher molecular weight that when layered on objects became quite hard upon cooling. This was used to cover objects that needed waterproofing,[3] such as scabbards and other items. Statuettes of household deities were also cast with this type of material in Japan, and probably also in China.

In North America, archaeological recovery has indicated bitumen was sometimes used to adhere stone projectile points to wooden shafts.[32] In Canada, aboriginal people used bitumen seeping out of the banks of the Athabasca and other rivers to waterproof birch bark canoes, and also heated it in smudge pots to ward off mosquitoes in the summer.

Asphalt Paving Cost Estimate

In 1553, Pierre Belon described in his work Observations that pissasphalto, a mixture of pitch and bitumen, was used in the Republic of Ragusa (now Dubrovnik, Croatia) for tarring of ships.

Macadam

Pave My Driveway Price

An 1838 edition of Mechanics Magazine cites an early use of asphalt in France. A pamphlet dated 1621, by “a certain Monsieur d’Eyrinys, states that he had discovered the existence (of asphaltum) in large quantities in the vicinity of Neufchatel”, and that he proposed to use it in a variety of ways – “principally in the construction of air-proof granaries, and in protecting, by means of the arches, the water-courses in the city of Paris from the intrusion of dirt and filth”, which at that time made the water unusable. “He expatiates also on the excellence of this material for forming level and durable terraces” in palaces, “the notion of forming such terraces in the streets not one likely to cross the brain of a Parisian of that generation”.

Paving Services Quotes

But the substance was generally neglected in France until the revolution of 1830. In the 1830s there was a surge of interest, and asphalt became widely used “for pavements, flat roofs, and the lining of cisterns, and in England, some use of it had been made of it for similar purposes”. Its rise in Europe was “a sudden phenomenon”, after natural deposits were found “in France at Osbann (Bas-Rhin), the Parc (Ain) and the Puy-de-la-Poix (Puy-de-Dôme)”, although it could also be made artificially.[35] One of the earliest uses in France was the laying of about 24,000 square yards of Seyssel asphalt at the Place de la Concorde in 1835.

Among the earlier uses of bitumen in the United Kingdom was for etching. William Salmon’s Polygraphice (1673) provides a recipe for varnish used in etching, consisting of three ounces of virgin wax, two ounces of mastic, and one ounce of asphaltum.[37] By the fifth edition in 1685, he had included more asphaltum recipes from other sources.

Asphalt Installation Price

The first British patent for the use of asphalt was “Cassell’s patent asphalte or bitumen” in 1834.[35] Then on 25 November 1837, Richard Tappin Claridge patented the use of Seyssel asphalt (patent #7849), for use in asphalte pavement,[39][40] having seen it employed in France and Belgium when visiting with Frederick Walter Simms, who worked with him on the introduction of asphalt to Britain.[41][42] Dr T. Lamb Phipson writes that his father, Samuel Ryland Phipson, a friend of Claridge, was also “instrumental in introducing the asphalte pavement (in 1836)”.[43] Indeed, mastic pavements had been previously employed at Vauxhall by a competitor of Claridge, but without success.

Driveway

Driveway Paving Cost Estimate

Claridge obtained a patent in Scotland on 27 March 1838, and obtained a patent in Ireland on 23 April 1838. In 1851, extensions for the 1837 patent and for both 1838 patents were sought by the trustees of a company previously formed by Claridge. Claridge’s Patent Asphalte Company—formed in 1838 for the purpose of introducing to Britain “Asphalte in its natural state from the mine at Pyrimont Seysell in France”,—”laid one of the first asphalt pavements in Whitehall”.  Trials were made of the pavement in 1838 on the footway in Whitehall, the stable at Knightsbridge Barracks,”and subsequently on the space at the bottom of the steps leading from Waterloo Place to St. James Park”. “The formation in 1838 of Claridge’s Patent Asphalte Company (with a distinguished list of aristocratic patrons, and Marc and Isambard Brunel as, respectively, a trustee and consulting engineer), gave an enormous impetus to the development of a British asphalt industry”.[45] “By the end of 1838, at least two other companies, Robinson’s and the Bastenne company, were in production”,[50] with asphalt being laid as paving at Brighton, Herne Bay, Canterbury, Kensington, the Strand, and a large floor area in Bunhill-row, while meantime Claridge’s Whitehall paving “continue(d) in good order”.

Asphalt And Pavement Contractor in Alberton ?

Commercial Paving Quotes For other uses, see Asphalt (disambiguation). Note: The terms bitumen and asphalt are mostly interchangeable, except where asphalt is used as a shorthand for asphalt concrete. Natural bitumen from the Dead Sea Refined asphalt The University of Queensland pitch drop experiment, demonstrating the viscosity of asphalt

Asphalt (/ˈæsˌfɔːlt, -ˌfɑːlt/), also known as bitumen (UK English: /ˈbɪəmən, ˈbɪtjʊmən/,[1] US English: /bɪˈt(j)mən, bˈt(j)mən/)[2] is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used.[3] The word is derived from the Ancient Greek ἄσφαλτος ásphaltos.[4]

The primary use (70%) of asphalt is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.[5]

The terms "asphalt" and "bitumen" are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, "asphalt" (or "asphalt cement") is commonly used for a refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called "bitumen", and geologists worldwide often prefer the term for the naturally occurring variety. Common colloquial usage often refers to various forms of asphalt as "tar", as in the name of the La Brea Tar Pits.

Naturally occurring asphalt is sometimes specified by the term "crude bitumen". Its viscosity is similar to that of cold molasses[6][7] while the material obtained from the fractional distillation of crude oil boiling at 525 °C (977 °F) is sometimes referred to as "refined bitumen". The Canadian province of Alberta has most of the world's reserves of natural asphalt in the Athabasca oil sands, which cover 142,000 square kilometres (55,000 sq mi), an area larger than England.[8]

The word "asphalt" is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word meaning "asphalt/bitumen/pitch",[9] which perhaps derives from ἀ-, "without" and σφάλλω (sfallō), "make fall".[10] The first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall.[11] From the Greek, the word passed into late Latin, and thence into French (asphalte) and English ("asphaltum" and "asphalt"). In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the "asphaltic concrete" used to pave roads.

The expression "bitumen" originated in the Sanskrit words jatu, meaning "pitch", and jatu-krit, meaning "pitch creating" or "pitch producing" (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally gwitu-men (pertaining to pitch), and by others, pixtumens (exuding or bubbling pitch), which was subsequently shortened to bitumen, thence passing via French into English. From the same root is derived the Anglo-Saxon word cwidu (mastix), the German word Kitt (cement or mastic) and the old Norse word kvada.[12]

In British English, "bitumen" is used instead of "asphalt". The word "asphalt" is instead used to refer to asphalt concrete, a mixture of construction aggregate and asphalt itself (also called "tarmac" in common parlance). Bitumen mixed with clay was usually called "asphaltum",[13] but the term is less commonly used today.[citation needed]

In Australian English, "bitumen" is often used as the generic term for road surfaces.

In American English, "asphalt" is equivalent to the British "bitumen". However, "asphalt" is also commonly used as a shortened form of "asphalt concrete" (therefore equivalent to the British "asphalt" or "tarmac").

In Canadian English, the word "bitumen" is used to refer to the vast Canadian deposits of extremely heavy crude oil,[14] while "asphalt" is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as "dilbit" in the Canadian petroleum industry, while bitumen "upgraded" to synthetic crude oil is known as "syncrude", and syncrude blended with bitumen is called "synbit".[15]

"Bitumen" is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. "Bituminous rock" is a form of sandstone impregnated with bitumen. The tar sands of Alberta, Canada are a similar material.

Neither of the terms "asphalt" or "bitumen" should be confused with tar or coal tars.[further explanation needed]

See also: Asphaltene

The components of asphalt include four main classes of compounds:

The naphthene aromatics and polar aromatics are typically the majority components. Most natural bitumens also contain organosulfur compounds, resulting in an overall sulfur content of up to 4%. Nickel and vanadium are found at <10 parts per million, as is typical of some petroleum.[5]

The substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase.[16] "It is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large".[17]

Asphalt may be confused with coal tar, which is a visually similar black, thermoplastic material produced by the destructive distillation of coal. During the early and mid-20th century, when town gas was produced, coal tar was a readily available byproduct and extensively used as the binder for road aggregates. The addition of coal tar to macadam roads led to the word "tarmac", which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, asphalt has completely overtaken the use of coal tar in these applications. Other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. "Pitch" is another term sometimes informally used at times to refer to asphalt, as in Pitch Lake.

Bituminous outcrop of the Puy de la Poix, Clermont-Ferrand, France

The majority of asphalt used commercially is obtained from petroleum.[18] Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.

Natural deposits of bitumen include lakes such as the Pitch Lake in Trinidad and Tobago and Lake Bermudez in Venezuela. Natural seeps occur in the La Brea Tar Pits and in the Dead Sea.

Bitumen also occurs in unconsolidated sandstones known as "oil sands" in Alberta, Canada, and the similar "tar sands" in Utah, US. The Canadian province of Alberta has most of the world's reserves, in three huge deposits covering 142,000 square kilometres (55,000 sq mi), an area larger than England or New York state. These bituminous sands contain 166 billion barrels (26.4×10^9 m3) of commercially established oil reserves, giving Canada the third largest oil reserves in the world. Although historically it was used without refining to pave roads, nearly all of the output is now used as raw material for oil refineries in Canada and the United States.[8]

The world's largest deposit of natural bitumen, known as the Athabasca oil sands, is located in the McMurray Formation of Northern Alberta. This formation is from the early Cretaceous, and is composed of numerous lenses of oil-bearing sand with up to 20% oil.[19] Isotopic studies show the oil deposits to be about 110 million years old.[20] Two smaller but still very large formations occur in the Peace River oil sands and the Cold Lake oil sands, to the west and southeast of the Athabasca oil sands, respectively. Of the Alberta deposits, only parts of the Athabasca oil sands are shallow enough to be suitable for surface mining. The other 80% has to be produced by oil wells using enhanced oil recovery techniques like steam-assisted gravity drainage.[21]

Much smaller heavy oil or bitumen deposits also occur in the Uinta Basin in Utah, US. The Tar Sand Triangle deposit, for example, is roughly 6% bitumen.[19]

Bitumen may occur in hydrothermal veins. An example of this is within the Uinta Basin of Utah, in the US, where there is a swarm of laterally and vertically extensive veins composed of a solid hydrocarbon termed Gilsonite. These veins formed by the polymerization and solidification of hydrocarbons that were mobilized from the deeper oil shales of the Green River Formation during burial and diagenesis.[22]

Bitumen is similar to the organic matter in carbonaceous meteorites.[23] However, detailed studies have shown these materials to be distinct.[24] The vast Alberta bitumen resources are considered to have started out as living material from marine plants and animals, mainly algae, that died millions of years ago when an ancient ocean covered Alberta. They were covered by mud, buried deeply over time, and gently cooked into oil by geothermal heat at a temperature of 50 to 150 °C (120 to 300 °F). Due to pressure from the rising of the Rocky Mountains in southwestern Alberta, 80 to 55 million years ago, the oil was driven northeast hundreds of kilometres and trapped into underground sand deposits left behind by ancient river beds and ocean beaches, thus forming the oil sands.[21]

The use of natural bitumen for waterproofing, and as an adhesive dates at least to the fifth millennium BC, with a crop storage basket discovered in Mehrgarh, of the Indus Valley Civilization, lined with it.[25] By the 3rd millennia BC refined rock asphalt was in use, in the region, and was used to waterproof the Great Bath, Mohenjo-daro.

In the ancient Middle East, the Sumerians used natural bitumen deposits for mortar between bricks and stones, to cement parts of carvings, such as eyes, into place, for ship caulking, and for waterproofing.[3] The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon.[26]

The 1 kilometre (0.62 mi) long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis (ca. 800 BC) was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent.[27]

Bitumen was used by ancient Egyptians to embalm mummies.[3][28] The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians' primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake).

Approximately 40 AD, Dioscorides described the Dead Sea material as Judaicum bitumen, and noted other places in the region where it could be found.[29] The Sidon bitumen is thought to refer to material found at Hasbeya.[30] Pliny refers also to bitumen being found in Epirus. It was a valuable strategic resource, the object of the first known battle for a hydrocarbon deposit—between the Seleucids and the Nabateans in 312 BC.[31]

In the ancient Far East, natural bitumen was slowly boiled to get rid of the higher fractions, leaving a thermoplastic material of higher molecular weight that when layered on objects became quite hard upon cooling. This was used to cover objects that needed waterproofing,[3] such as scabbards and other items. Statuettes of household deities were also cast with this type of material in Japan, and probably also in China.

In North America, archaeological recovery has indicated bitumen was sometimes used to adhere stone projectile points to wooden shafts.[32] In Canada, aboriginal people used bitumen seeping out of the banks of the Athabasca and other rivers to waterproof birch bark canoes, and also heated it in smudge pots to ward off mosquitoes in the summer.[21]

In 1553, Pierre Belon described in his work Observations that pissasphalto, a mixture of pitch and bitumen, was used in the Republic of Ragusa (now Dubrovnik, Croatia) for tarring of ships.[33]

An 1838 edition of Mechanics Magazine cites an early use of asphalt in France. A pamphlet dated 1621, by "a certain Monsieur d'Eyrinys, states that he had discovered the existence (of asphaltum) in large quantities in the vicinity of Neufchatel", and that he proposed to use it in a variety of ways – "principally in the construction of air-proof granaries, and in protecting, by means of the arches, the water-courses in the city of Paris from the intrusion of dirt and filth", which at that time made the water unusable. "He expatiates also on the excellence of this material for forming level and durable terraces" in palaces, "the notion of forming such terraces in the streets not one likely to cross the brain of a Parisian of that generation".[34]

But the substance was generally neglected in France until the revolution of 1830. In the 1830s there was a surge of interest, and asphalt became widely used "for pavements, flat roofs, and the lining of cisterns, and in England, some use of it had been made of it for similar purposes". Its rise in Europe was "a sudden phenomenon", after natural deposits were found "in France at Osbann (Bas-Rhin), the Parc (Ain) and the Puy-de-la-Poix (Puy-de-Dôme)", although it could also be made artificially.[35] One of the earliest uses in France was the laying of about 24,000 square yards of Seyssel asphalt at the Place de la Concorde in 1835.[36]

Among the earlier uses of bitumen in the United Kingdom was for etching. William Salmon's Polygraphice (1673) provides a recipe for varnish used in etching, consisting of three ounces of virgin wax, two ounces of mastic, and one ounce of asphaltum.[37] By the fifth edition in 1685, he had included more asphaltum recipes from other sources.[38]

The first British patent for the use of asphalt was "Cassell's patent asphalte or bitumen" in 1834.[35] Then on 25 November 1837, Richard Tappin Claridge patented the use of Seyssel asphalt (patent #7849), for use in asphalte pavement,[39][40] having seen it employed in France and Belgium when visiting with Frederick Walter Simms, who worked with him on the introduction of asphalt to Britain.[41][42] Dr T. Lamb Phipson writes that his father, Samuel Ryland Phipson, a friend of Claridge, was also "instrumental in introducing the asphalte pavement (in 1836)".[43] Indeed, mastic pavements had been previously employed at Vauxhall by a competitor of Claridge, but without success.[36]

Claridge obtained a patent in Scotland on 27 March 1838, and obtained a patent in Ireland on 23 April 1838. In 1851, extensions for the 1837 patent and for both 1838 patents were sought by the trustees of a company previously formed by Claridge.[35][44][45][46] Claridge's Patent Asphalte Company—formed in 1838 for the purpose of introducing to Britain "Asphalte in its natural state from the mine at Pyrimont Seysell in France",[47]—"laid one of the first asphalt pavements in Whitehall".[48] Trials were made of the pavement in 1838 on the footway in Whitehall, the stable at Knightsbridge Barracks,[47][49] "and subsequently on the space at the bottom of the steps leading from Waterloo Place to St. James Park".[49] "The formation in 1838 of Claridge's Patent Asphalte Company (with a distinguished list of aristocratic patrons, and Marc and Isambard Brunel as, respectively, a trustee and consulting engineer), gave an enormous impetus to the development of a British asphalt industry".[45] "By the end of 1838, at least two other companies, Robinson's and the Bastenne company, were in production",[50] with asphalt being laid as paving at Brighton, Herne Bay, Canterbury, Kensington, the Strand, and a large floor area in Bunhill-row, while meantime Claridge's Whitehall paving "continue(d) in good order".[51]

In 1838, there was a flurry of entrepreneurial activity involving asphalt, which had uses beyond paving. For example, asphalt could also be used for flooring, damp proofing in buildings, and for waterproofing of various types of pools and baths, both of which were also proliferating in the 19th century.[3][35][52] On the London stockmarket, there were various claims as to the exclusivity of asphalt quality from France, Germany and England. And numerous patents were granted in France, with similar numbers of patent applications being denied in England due to their similarity to each other. In England, "Claridge's was the type most used in the 1840s and 50s".[50]

In 1914, Claridge's Company entered into a joint venture to produce tar-bound macadam,[53] with materials manufactured through a subsidiary company called Clarmac Roads Ltd.[54] Two products resulted, namely Clarmac, and Clarphalte, with the former being manufactured by Clarmac Roads and the latter by Claridge's Patent Asphalte Co., although Clarmac was more widely used.[55][note 1] However, the First World War ruined the Clarmac Company, which entered into liquidation in 1915.[57][58] The failure of Clarmac Roads Ltd had a flow-on effect to Claridge's Company, which was itself compulsorily wound up,[59] ceasing operations in 1917,[60][61] having invested a substantial amount of funds into the new venture, both at the outset[59] and in a subsequent attempt to save the Clarmac Company.[57]

The first use of bitumen in the New World was by indigenous peoples. On the west coast, as early as the 13th century, the Tongva, Luiseño and Chumash peoples collected the naturally occurring bitumen that seeped to the surface above underlying petroleum deposits. All three groups used the substance as an adhesive. It is found on many different artifacts of tools and ceremonial items. For example, it was used on rattles to adhere gourds or turtle shells to rattle handles. It was also used in decorations. Small round shell beads were often set in asphaltum to provide decorations. It was used as a sealant on baskets to make them watertight for carrying water, possibly poisoning those who drank the water.[62] Asphalt was used also to seal the planks on ocean-going canoes.

Asphalt was first used to pave streets in the 1870s. At first naturally occurring "bituminous rock" was used, such as at Ritchie Mines in Macfarlan in Ritchie County, West Virginia from 1852 to 1873. In 1876, asphalt-based paving was used to pave Pennsylvania Avenue in Washington DC, in time for the celebration of the national centennial.[63] In the horse-drawn era, streets were unpaved and covered with dirt or gravel. However, that produced uneven wear, opened new hazards for pedestrians and made for dangerous potholes for bicycles and for motor vehicles. Manhattan alone had 130,000 horses in 1900, pulling streetcars, wagons, and carriages, and leaving their waste behind. They were not fast, and pedestrians could dodge and scramble their way across the crowded streets. Small towns continued to rely on dirt and gravel, but larger cities wanted much better streets. They looked to wood or granite blocks by the 1850s.[64] In 1890, a third of Chicago's 2000 miles of streets were paved, chiefly with wooden blocks, which gave better traction than mud. Brick surfacing was a good compromise, but even better was asphalt paving, which was easy to install and to cut through to get at sewers. With London and Paris serving as models, Washington laid 400,000 square yards of asphalt paving by 1882; it became the model for Buffalo, Philadelphia and elsewhere. By the end of the century, American cities boasted 30 million square yards of asphalt paving, well ahead of brick.[65] The streets became faster and more dangerous so electric traffic lights were installed. Electric trolleys (at 12 miles per hour) became the main transportation service for middle class shoppers and office workers until they bought automobiles after 1945 and commuted from more distant suburbs in privacy and comfort on asphalt highways.[66]

See also: Bitumount and History of the petroleum industry in Canada (oil sands and heavy oil)

Canada has the world's largest deposit of natural bitumen in the Athabasca oil sands, and Canadian First Nations along the Athabasca River had long used it to waterproof their canoes. In 1719, a Cree named Wa-Pa-Su brought a sample for trade to Henry Kelsey of the Hudson’s Bay Company, who was the first recorded European to see it. However, it wasn't until 1787 that fur trader and explorer Alexander MacKenzie saw the Athabasca oil sands and said, "At about 24 miles from the fork (of the Athabasca and Clearwater Rivers) are some bituminous fountains into which a pole of 20 feet long may be inserted without the least resistance."[21]

The value of the deposit was obvious from the start, but the means of extracting the bitumen was not. The nearest town, Fort McMurray, Alberta, was a small fur trading post, other markets were far away, and transportation costs were too high to ship the raw bituminous sand for paving. In 1915, Sidney Ells of the Federal Mines Branch experimented with separation techniques and used the product to pave 600 feet of road in Edmonton, Alberta. Other roads in Alberta were paved with material extracted from oil sands, but it was generally not economic. During the 1920s Dr. Karl A. Clark of the Alberta Research Council patented a hot water oil separation process and entrepreneur Robert C. Fitzsimmons[67] built the Bitumount oil separation plant, which between 1925 and 1958 produced up to 300 barrels (50 m3) per day of bitumen using Dr. Clark's method. Most of the bitumen was used for waterproofing roofs, but other uses included fuels, lubrication oils, printers ink, medicines, rust- and acid-proof paints, fireproof roofing, street paving, patent leather, and fence post preservatives.[21] Eventually Fitzsimmons ran out of money and the plant was taken over by the Alberta government. Today the Bitumount plant is a Provincial Historic Site.[68]

Bitumen was used in early photographic technology. In 1826 or 1827, it was used by French scientist Joseph Nicéphore Niépce to make the oldest surviving photograph from nature. The bitumen was thinly coated onto a pewter plate which was then exposed in a camera. Exposure to light hardened the bitumen and made it insoluble, so that when it was subsequently rinsed with a solvent only the sufficiently light-struck areas remained. Many hours of exposure in the camera were required, making bitumen impractical for ordinary photography, but from the 1850s to the 1920s it was in common use as a photoresist in the production of printing plates for various photomechanical printing processes.[69][70]

Bitumen was the nemesis of many artists during the 19th century. Although widely used for a time, it ultimately proved unstable for use in oil painting, especially when mixed with the most common diluents, such as linseed oil, varnish and turpentine. Unless thoroughly diluted, bitumen never fully solidifies and will in time corrupt the other pigments with which it comes into contact. The use of bitumen as a glaze to set in shadow or mixed with other colors to render a darker tone resulted in the eventual deterioration of many paintings, for instance those of Delacroix. Perhaps the most famous example of the destructiveness of bitumen is Théodore Géricault's Raft of the Medusa (1818–1819), where his use of bitumen caused the brilliant colors to degenerate into dark greens and blacks and the paint and canvas to buckle.[71]

The vast majority of refined asphalt is used in construction: primarily as a constituent of products used in paving and roofing applications. According to the requirements of the end use, asphalt is produced to specification. This is achieved either by refining or blending. It is estimated that the current world use of asphalt is approximately 102 million tonnes per year. Approximately 85% of all the asphalt produced is used as the binder in asphalt concrete for roads. It is also used in other paved areas such as airport runways, car parks and footways. Typically, the production of asphalt concrete involves mixing fine and coarse aggregates such as sand, gravel and crushed rock with asphalt, which acts as the binding agent. Other materials, such as recycled polymers (e.g., rubber tyres), may be added to the asphalt to modify its properties according to the application for which the asphalt is ultimately intended.

A further 10% of global asphalt production is used in roofing applications, where its waterproofing qualities are invaluable. The remaining 5% of asphalt is used mainly for sealing and insulating purposes in a variety of building materials, such as pipe coatings, carpet tile backing and paint. Asphalt is applied in the construction and maintenance of many structures, systems, and components, such as the following:

Main article: Asphalt concrete

The largest use of asphalt is for making asphalt concrete for road surfaces; this accounts for approximately 85% of the asphalt consumed in the United States. Asphalt concrete pavement mixes are typically composed of 5% asphalt cement and 95% aggregates (stone, sand, and gravel). Due to its highly viscous nature, asphalt cement must be heated so it can be mixed with the aggregates at the asphalt mixing facility. The temperature required varies depending upon characteristics of the asphalt and the aggregates, but warm-mix asphalt technologies allow producers to reduce the temperature required. There are about 4,000 asphalt concrete mixing plants in the US, and a similar number in Europe.[72]

When maintenance is performed on asphalt pavements, such as milling to remove a worn or damaged surface, the removed material can be returned to a facility for processing into new pavement mixtures. The asphalt in the removed material can be reactivated and put back to use in new pavement mixes.[73] With some 95% of paved roads being constructed of or surfaced with asphalt,[74] a substantial amount of asphalt pavement material is reclaimed each year. According to industry surveys conducted annually by the Federal Highway Administration and the National Asphalt Pavement Association, more than 99% of the asphalt removed each year from road surfaces during widening and resurfacing projects is reused as part of new pavements, roadbeds, shoulders and embankments.[75]

Asphalt concrete paving is widely used in airports around the world. Due to the sturdiness and ability to be repaired quickly, it is widely used for runways.

Further information: Fibre mastic asphalt

Mastic asphalt is a type of asphalt that differs from dense graded asphalt (asphalt concrete) in that it has a higher asphalt (binder) content, usually around 7–10% of the whole aggregate mix, as opposed to rolled asphalt concrete, which has only around 5% asphalt. This thermoplastic substance is widely used in the building industry for waterproofing flat roofs and tanking underground. Mastic asphalt is heated to a temperature of 210 °C (410 °F) and is spread in layers to form an impervious barrier about 20 millimeters (0.8 inches) thick.

A number of technologies allow asphalt to be mixed at much lower temperatures. These involve mixing with petroleum solvents to form "cutbacks" with reduced melting point or mixing with water to turn the asphalt into an emulsion. Asphalt emulsions contain up to 70% asphalt and typically less than 1.5% chemical additives. There are two main types of emulsions with different affinity for aggregates, cationic and anionic. Asphalt emulsions are used in a wide variety of applications. Chipseal involves spraying the road surface with asphalt emulsion followed by a layer of crushed rock, gravel or crushed slag. Slurry seal involves the creation of a mixture of asphalt emulsion and fine crushed aggregate that is spread on the surface of a road. Cold-mixed asphalt can also be made from asphalt emulsion to create pavements similar to hot-mixed asphalt, several inches in depth, and asphalt emulsions are also blended into recycled hot-mix asphalt to create low-cost pavements.

Main article: Synthetic crude oil See also: Petroleum production in Canada

Synthetic crude oil, also known as syncrude, is the output from a bitumen upgrader facility used in connection with oil sand production in Canada. Bituminous sands are mined using enormous (100 ton capacity) power shovels and loaded into even larger (400 ton capacity) dump trucks for movement to an upgrading facility. The process used to extract the bitumen from the sand is a hot water process originally developed by Dr. Karl Clark of the University of Alberta during the 1920s. After extraction from the sand, the bitumen is fed into a bitumen upgrader which converts it into a light crude oil equivalent. This synthetic substance is fluid enough to be transferred through conventional oil pipelines and can be fed into conventional oil refineries without any further treatment. By 2015 Canadian bitumen upgraders were producing over 1 million barrels (160×10^3 m3) per day of synthetic crude oil, of which 75% was exported to oil refineries in the United States.[76]

In Alberta, five bitumen upgraders produce synthetic crude oil and a variety of other products: The Suncor Energy upgrader near Fort McMurray, Alberta produces synthetic crude oil plus diesel fuel; the Syncrude Canada, Canadian Natural Resources, and Nexen upgraders near Fort McMurray produce synthetic crude oil; and the Shell Scotford Upgrader near Edmonton produces synthetic crude oil plus an intermediate feedstock for the nearby Shell Oil Refinery.[77] A sixth upgrader, under construction in 2015 near Redwater, Alberta, will upgrade half of its crude bitumen directly to diesel fuel, with the remainder of the output being sold as feedstock to nearby oil refineries and petrochemical plants.[78]

See also: Western Canadian Select

Canadian bitumen does not differ substantially from oils such as Venezuelan extra-heavy and Mexican heavy oil in chemical composition, and the real difficulty is moving the extremely viscous bitumen through oil pipelines to the refinery. Many modern oil refineries are extremely sophisticated and can process non-upgraded bitumen directly into products such as gasoline, diesel fuel, and refined asphalt without any preprocessing. This is particularly common in areas such as the US Gulf coast, where refineries were designed to process Venezuelan and Mexican oil, and in areas such as the US Midwest where refineries were rebuilt to process heavy oil as domestic light oil production declined. Given the choice, such heavy oil refineries usually prefer to buy bitumen rather than synthetic oil because the cost is lower, and in some cases because they prefer to produce more diesel fuel and less gasoline.[77] By 2015 Canadian production and exports of non-upgraded bitumen exceeded that of synthetic crude oil at over 1.3 million barrels (210×10^3 m3) per day, of which about 65% was exported to the United States.[76]

Because of the difficulty of moving crude bitumen through pipelines, non-upgraded bitumen is usually diluted with natural-gas condensate in a form called dilbit or with synthetic crude oil, called synbit. However, to meet international competition, much non-upgraded bitumen is now sold as a blend of multiple grades of bitumen, conventional crude oil, synthetic crude oil, and condensate in a standardized benchmark product such as Western Canadian Select. This sour, heavy crude oil blend is designed to have uniform refining characteristics to compete with internationally marketed heavy oils such as Mexican Mayan or Arabian Dubai Crude.[77]

Asphalt was used starting in the 1960s as an hydrophobic matrix aiming to encapsulate radioactive waste such as medium-activity salts (mainly soluble sodium nitrate and sodium sulfate) produced by the reprocessing of spent nuclear fuels or radioactive sludges from sedimentation ponds.[79][80] Bituminised radioactive waste containing highly radiotoxic alpha-emitting transuranic elements from nuclear reprocessing plants have been produced at industrial scale in France, Belgium and Japan, but this type of waste conditioning has been abandoned because operational safety issues (risks of fire, as occurred in a bituminisation plant at Tokai Works in Japan)[81][82] and long-term stability problems related to their geological disposal in deep rock formations. One of the main problem is the swelling of asphalt exposed to radiation and to water. Asphalt swelling is first induced by radiation because of the presence of hydrogen gas bubbles generated by alpha and gamma radiolysis.[83][84] A second mechanism is the matrix swelling when the encapsulated hygroscopic salts exposed to water or moisture start to rehydrate and to dissolve. The high concentration of salt in the pore solution inside the bituminised matrix is then responsible for osmotic effects inside the bituminised matrix. The water moves in the direction of the concentrated salts, the asphalt acting as a semi-permeable membrane. This also causes the matrix to swell. The swelling pressure due to osmotic effect under constant volume can be as high as 200 bar. If not properly managed, this high pressure can cause fractures in the near field of a disposal gallery of bituminised medium-level waste. When the bituminised matrix has been altered by swelling, encapsulated radionuclides are easily leached by the contact of ground water and released in the geosphere. The high ionic strength of the concentrated saline solution also favours the migration of radionuclides in clay host rocks. The presence of chemically reactive nitrate can also affect the redox conditions prevailing in the host rock by establishing oxidizing conditions, preventing the reduction of redox-sensitive radionuclides. Under their higher valences, radionuclides of elements such as selenium, technetium, uranium, neptunium and plutonium have a higher solubility and are also often present in water as non-retarded anions. This makes the disposal of medium-level bituminised waste very challenging.

Different type of asphalt have been used: blown bitumen (partly oxidized with air oxygen at high temperature after distillation, and harder) and direct distillation bitumen (softer). Blown bitumens like Mexphalte, with a high content of saturated hydrocarbons, are more easily biodegraded by microorganisms than direct distillation bitumen, with a low content of saturated hydrocarbons and a high content of aromatic hydrocarbons.[85]

Concrete encapsulation of radwaste is presently considered a safer alternative by the nuclear industry and the waste management organisations.

Roofing shingles account for most of the remaining asphalt consumption. Other uses include cattle sprays, fence-post treatments, and waterproofing for fabrics. Asphalt is used to make Japan black, a lacquer known especially for its use on iron and steel, and it is also used in paint and marker inks by some exterior paint supply companies to increase the weather resistance and permanence of the paint or ink, and to make the color darker.[86] Asphalt is also used to seal some alkaline batteries during the manufacturing process.

Typical asphalt plant for making asphalt

About 40,000,000 tons were produced in 1984.[needs update] It is obtained as the "heavy" (i.e., difficult to distill) fraction. Material with a boiling point greater than around 500 °C is considered asphalt. Vacuum distillation separates it from the other components in crude oil (such as naphtha, gasoline and diesel). The resulting material is typically further treated to extract small but valuable amounts of lubricants and to adjust the properties of the material to suit applications. In a de-asphalting unit, the crude asphalt is treated with either propane or butane in a supercritical phase to extract the lighter molecules, which are then separated. Further processing is possible by "blowing" the product: namely reacting it with oxygen. This step makes the product harder and more viscous.[5]

Asphalt is typically stored and transported at temperatures around 150 °C (302 °F). Sometimes diesel oil or kerosene are mixed in before shipping to retain liquidity; upon delivery, these lighter materials are separated out of the mixture. This mixture is often called "bitumen feedstock", or BFS. Some dump trucks route the hot engine exhaust through pipes in the dump body to keep the material warm. The backs of tippers carrying asphalt, as well as some handling equipment, are also commonly sprayed with a releasing agent before filling to aid release. Diesel oil is no longer used as a release agent due to environmental concerns.

Main article: Oil sands

Naturally occurring crude bitumen impregnated in sedimentary rock is the prime feed stock for petroleum production from "oil sands", currently under development in Alberta, Canada. Canada has most of the world's supply of natural bitumen, covering 140,000 square kilometres[14] (an area larger than England), giving it the second-largest proven oil reserves in the world. The Athabasca oil sands are the largest bitumen deposit in Canada and the only one accessible to surface mining, although recent technological breakthroughs have resulted in deeper deposits becoming producible by in situ methods. Because of oil price increases after 2003, producing bitumen became highly profitable, but as a result of the decline after 2014 it became uneconomic to build new plants again. By 2014, Canadian crude bitumen production averaged about 2.3 million barrels (370,000 m3) per day and was projected to rise to 4.4 million barrels (700,000 m3) per day by 2020.[15] The total amount of crude bitumen in Alberta that could be extracted is estimated to be about 310 billion barrels (50×10^9 m3),[8] which at a rate of 4,400,000 barrels per day (700,000 m3/d) would last about 200 years.

Main articles: Peak oil, Global warming, and Bioasphalt

Although uncompetitive economically, asphalt can be made from nonpetroleum-based renewable resources such as sugar, molasses and rice, corn and potato starches. Asphalt can also be made from waste material by fractional distillation of used motor oil, which is sometimes otherwise disposed of by burning or dumping into landfills. Use of motor oil may cause premature cracking in colder climates, resulting in roads that need to be repaved more frequently.[87]

Nonpetroleum-based asphalt binders can be made light-colored. Lighter-colored roads absorb less heat from solar radiation, reducing their contribution to the urban heat island effect.[88] Parking lots that use asphalt alternatives are called green parking lots.

Selenizza is a naturally occurring solid hydrocarbon bitumen found in native deposits in Selenice, in Albania, the only European asphalt mine still in use. The bitumen is found in the form of veins, filling cracks in a more or less horizontal direction. The bitumen content varies from 83% to 92% (soluble in carbon disulphide), with a penetration value near to zero and a softening point (ring and ball) around 120 °C. The insoluble matter, consisting mainly of silica ore, ranges from 8% to 17%.

Albanian bitumen extraction has a long history and was practiced in an organized way by the Romans. After centuries of silence, the first mentions of Albanian bitumen appeared only in 1868, when the Frenchman Coquand published the first geological description of the deposits of Albanian bitumen. In 1875, the exploitation rights were granted to the Ottoman government and in 1912, they were transferred to the Italian company Simsa. Since 1945, the mine was exploited by the Albanian government and from 2001 to date, the management passed to a French company, which organized the mining process for the manufacture of the natural bitumen on an industrial scale.[89]

Today the mine is predominantly exploited in an open pit quarry but several of the many underground mines (deep and extending over several km) still remain viable. Selenizza is produced primarily in granular form, after melting the bitumen pieces selected in the mine.

Selenizza[90] is mainly used as an additive in the road construction sector. It is mixed with traditional asphalt to improve both the viscoelastic properties and the resistance to ageing. It may be blended with the hot asphalt in tanks, but its granular form allows it to be fed in the mixer or in the recycling ring of normal asphalt plants. Other typical applications include the production of mastic asphalts for sidewalks, bridges, car-parks and urban roads as well as drilling fluid additives for the oil and gas industry. Selenizza is available in powder or in granular material of various particle sizes and is packaged in sacks or in thermal fusible polyethylene bags.

A life-cycle assessment study of the natural selenizza compared with petroleum asphalt has shown that the environmental impact of the selenizza is about half the impact of the road asphalt produced in oil refineries in terms of carbon dioxide emission.[91]

People can be exposed to asphalt in the workplace by breathing in fumes or skin absorption. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit of 5 mg/m3 over a 15-minute period.[92]

Asphalt is basically an inert material that must be heated or diluted to a point where it becomes workable for the production of materials for paving, roofing, and other applications. In examining the potential health hazards associated with asphalt, the International Agency for Research on Cancer (IARC) determined that it is the application parameters, predominantly temperature, that affect occupational exposure and the potential bioavailable carcinogenic hazard/risk of the asphalt emissions.[93] In particular, temperatures greater than 199 °C (390 °F), were shown to produce a greater exposure risk than when asphalt was heated to lower temperatures, such as those typically used in asphalt pavement mix production and placement.[94] IARC has classified asphalt as a Class 2B possible carcinogen.

An asphalt mixing plant for hot aggregate
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  47. ^ a b "Joint Stock Companies (description of asphalte use by Claridge's company)". The Civil Engineer and Architects Journal. Vol. 1. London. October 1837 – December 1838. p. 199. Retrieved 16 November 2009.  Full text at Internet Archive (archive.org). Alternative viewing at: https://books.google.com/books?id=sQ5AAAAAYAAJ&pg
  48. ^ Miles, Lewis (2000), pp.10.06.1–2
  49. ^ a b Comments on asphalt patents of R.T. Claridge, Esq (1904), p.18
  50. ^ a b Miles, Lewis (2000), p.10.06.2
  51. ^ "1838 bitumen UK uses by Robinson's and Claridge's companies, & the Bastenne company". The Mechanic's magazine, museum, register, journal and gazette. 29. London: W.A. Robertson. 22 September 1838. p. 448. 
  52. ^ Gerhard, W.M. Paul (1908). Modern Baths and Bath Houses (1st ed.). New York: John Wiley and Sons.  (Enter "asphalt" into the search field for list of pages discussing the subject)
  53. ^ "Claridge's Patent Asphalte Co. ventures into tarred slag macadam", Concrete and Constructional Engineering, London, IX (1): 760, January 1914, retrieved 15 June 2010 
  54. ^ "Registration of Clarmac Roads", The Law Reports: Chancery Division, Vol. 1: 544–547, 1921, retrieved 17 June 2010 
  55. ^ "Clarmac and Clarphalte", The Building News and Engineering Journal, Vol. 109: July to December 1915 (No. 3157): 2–4 (n13–15 in electronic page field), 7 July 1915, retrieved 18 June 2010 
  56. ^ Roads laid with Clarmac The Building News and Engineering Journal, 1915 109 (3157), p.3 (n14 in electronic field).
  57. ^ a b Clarmac financial difficults due to WW1 Debentures deposited The Law Reports: Chancery Division, (1921) Vol. 1 p.545. Retrieved 17 June 2010.
  58. ^ "Notice of the Winding up of Clarmac Roads", The London Gazette (29340): 10568, 26 October 1915, retrieved 15 June 2010 
  59. ^ a b Claridge's Patent Asphalte Co. compulsorily wound up Funds invested in new company The Law Times Reports (1921) Vol.125, p.256. Retrieved 15 June 2010.
  60. ^ "Claridge's Patent Asphalte Co. winds up 10 November 1917". The London Gazette. 16 November 1917. p. 11863. 
  61. ^ Hobhouse, Hermione (General Editor) (1994). "British History Online". 'Cubitt Town: Riverside area: from Newcastle Drawdock to Cubitt Town Pier', Survey of London: volumes 43 and 44: Poplar, Blackwall and Isle of Dogs. pp. 528–532 (see text at refs 507 & 510). Retrieved 8 November 2009. 
  62. ^ Stockton, Nick (23 June 2017). "Plastic Water Bottles Might Have Poisoned Ancient Californians". Wired. Retrieved 26 June 2017. 
  63. ^ McNichol, Dan (2005). Paving the Way: Asphalt in America. Lanham, MD: National Asphalt Pavement Association. ISBN 0-914313-04-5. Archived from the original on 2006-08-29. 
  64. ^ David O. Whitten, "A Century of Parquet Pavements: Wood as a Paving Material In The United States And Abroad, 1840-1940." Essays in Economic and Business History 15 (1997): 209-26.
  65. ^ Arthur Maier Schlesinger, The Rise of the City: 1878-1898 (1933) p 88-93.
  66. ^ John D. Fairfield, "Rapid Transit: Automobility and Settlement in Urban America" Reviews in American History 23#1 (1995), pp. 80-85 online.
  67. ^ "Robert C. Fitzsimmons (1881–1971)". Canadian Petroleum Hall of Fame. 2010. Retrieved 2016-01-20. 
  68. ^ "Bitumount". Government of Alberta. 2016. Retrieved 2016-01-20. 
  69. ^ Niépce Museum history pages. Retrieved 27 October 2012. Archived 3 August 2007 at the Wayback Machine.
  70. ^ The First Photograph (Harry Ransom Center, University of Texas at Austin). Retrieved 27 October 2012.
  71. ^ Spiegelman, Willard (2009-08-21). "Revolutionary Romanticism: 'The Raft of the Medusa' brought energy to French art". The Wall Street Journal. New York City. Retrieved 2016-01-27. 
  72. ^ The Asphalt Paving Industry: A Global Perspective, 2nd Edition (PDF). Lanham, Maryland, and Brussels: National Asphalt Pavement Association and European Asphalt Pavement Association. February 2011. ISBN 0-914313-06-1. Retrieved 27 September 2012. 
  73. ^ "How Should We Express RAP and RAS Contents?". Asphalt Technology E-News. 26 (2). 2014. Archived from the original on 9 June 2015. Retrieved 2015-08-13. 
  74. ^ "Highway Statistics Series: Public Road Length Miles by Type of Surface and Ownership". Federal Highway Administration. 2013-10-01. Retrieved 2015-08-13. 
  75. ^ "Asphalt Pavement Recycling". Annual Asphalt Pavement Industry Survey on Recycled Materials and Warm-Mix Asphalt Usage: 2009–2013. National Asphalt Pavement Association. Retrieved 13 August 2015. 
  76. ^ a b "Crude Oil and Petroleum Products". National Energy Board of Canada. Retrieved January 21, 2016. 
  77. ^ a b c "2015 CAPP Crude Oil Forecast, Markets & Transportation". Canadian Association of Petroleum Producers. Archived from the original on 20 January 2016. Retrieved January 21, 2016. 
  78. ^ "The Project". North West Redwater Partnership. Retrieved January 21, 2016. 
  79. ^ Rodier, J., Scheidhauer, J., & Malabre, M. (1961). The conditioning of radioactive waste by bitumen (No. CEA-R—1992). CEA Marcoule.
  80. ^ Lefillatre, G., Rodier, J., Hullo, R., Cudel, Y., & Rodi, L. (1969). Use of a thin-film evaporator for bitumen coating of radioactive concentrates (No. CEA-R—3742). CEA Marcoule.
  81. ^ Sato, Y., Miura, A., Kato, Y., Suzuki, H., Shigetome, Y., Koyama, T., ... & Yamanouchi, T. (2000). Study on the cause of the fire and explosion incident at Bituminization Demonstration Facility of PNC Tokai Works. In Nuclear waste: from research to industrial maturity. International conference (pp. 179–190).
  82. ^ Okada, K., Nur, R. M., & Fujii, Y. (1999). The formation of explosive compounds in bitumen/nitrate mixtures. Journal of hazardous materials, 69(3), 245–256.
  83. ^ Johnson, D.I., Hitchon, J.W., & Phillips, D.C. (1986). Further observations of the swelling of bitumens and simulated bitumen wasteforms during γ-irradiation (No. AERE-R—12292). UKAEA Harwell Lab. Materials Development Division.
  84. ^ Phillips, D. C., Hitchon, J. W., Johnson, D. I., & Matthews, J. R. (1984). The radiation swelling of bitumens and bitumenised wastes. Journal of nuclear materials, 125(2), 202–218.
  85. ^ Ait-Langomazino, N., Sellier, R., Jouquet, G., & Trescinski, M. (1991). Microbial degradation of bitumen. Experientia, 47(6), 533–539.
  86. ^ Mohd, Meraj Jafri; Singh, D. K. (march 2013). "Cashew Nutshell Liquid Resin" (PDF). IJRREST: International Journal of Research Review in Engineering Science and Technology. 2: 60–65.  Check date values in: |date= (help)
  87. ^ Hesp, Simon A.M.; Herbert F. Shurvell (2010). "X-ray fluorescence detection of waste engine oil residue in asphalt and its effect on cracking in service". International Journal of Pavement Engineering. 11 (6): 541–553. doi:10.1080/10298436.2010.488729. ISSN 1029-8436. Retrieved 2014-03-24. 
  88. ^ Heat Island Effect. From the website of the US Environmental Protection Agency.
  89. ^ Giavarini, Carlo (March 2013). Six Thousand Years of Asphalt. SITEB. pp. 71–78. ISBN 978-88-908408-3-8. 
  90. ^ [3], Selenice Bitumi for more information about Selenizza
  91. ^ Giavarini, C.; Pellegrini, A. "Life cycle assessment of Selenice asphalt compared with petroleum bitumen". The 1st Albanian Congress on Roads: 234–237. 
  92. ^ "CDC – NIOSH Pocket Guide to Chemical Hazards – Asphalt fumes". www.cdc.gov. Retrieved 2015-11-27. 
  93. ^ IARC (2013). Bitumens and Bitumen Emissions, and Some N- and S-Heterocyclic Polycyclic Aromatic Hydrocarbons. 103. Lyon, France: International Agency for Research on Cancer. ISBN 978-92-832-1326-0. Retrieved 2015-12-07. 
  94. ^ Cavallari, J. M.; Zwack, L. M.; Lange, C. R.; Herrick, R. F.; Mcclean, M. D. (2012). "Temperature-Dependent Emission Concentrations of Polycyclic Aromatic Hydrocarbons in Paving and Built-Up Roofing Asphalts". Annals of Occupational Hygiene. 56 (2): 148–160. doi:10.1093/annhyg/mer107 . ISSN 0003-4878. 
  95. ^ "Contacto – Eco Roofing". epdmecoroofing.com. 
  96. ^ "Follow the evolution of the road from path to pavement". 


Brick

Driveway Pavers Near Me A high-speed toll booth on SR 417 near Orlando, Florida, United States. A toll collection area in the United Kingdom. Hong Kong toll booth.

A toll road, also known as a turnpike or tollway, is a public or private road for which a fee (or toll) is assessed for passage. It is a form of road pricing typically implemented to help recoup the cost of road construction and maintenance.

Toll roads have existed in some form since antiquity, with tolls levied on passing travellers on foot, wagon or horseback; but their prominence increased with the rise of the automobile,[citation needed] and many modern tollways charge fees for motor vehicles exclusively. The amount of the toll usually varies by vehicle type, weight, or number of axles, with freight trucks often charged higher rates than cars.

Tolls are often collected at toll booths, toll houses, plazas, stations, bars, or gates. Some toll collection points are unmanned and the user deposits money in a machine which opens the gate once the correct toll has been paid. To cut costs and minimise time delay many tolls today are collected by some form of automatic or electronic toll collection equipment which communicates electronically with a toll payer's transponder. Some electronic toll roads also maintain a system of toll booths so people without transponders can still pay the toll, but many newer roads now use automatic number plate recognition to charge drivers who use the road without a transponder, and some older toll roads are being upgraded with such systems.

Criticisms of toll roads include the time taken to stop and pay the toll, and the cost of the toll booth operators—up to about one third of revenue in some cases. Automated toll paying systems help minimise both of these. Others object to paying "twice" for the same road: in fuel taxes and with tolls.

In addition to toll roads, toll bridges and toll tunnels are also used by public authorities to generate funds to repay the cost of building the structures. Some tolls are set aside to pay for future maintenance or enhancement of infrastructure, or are applied as a general fund by local governments, not being earmarked for transport facilities. This is sometimes limited or prohibited by central government legislation. Also road congestion pricing schemes have been implemented in a limited number of urban areas as a transportation demand management tool to try to reduce traffic congestion and air pollution.[1]

A table of tolls in pre-decimal currency for the College Road, Dulwich, London SE21 tollgate.

Toll roads have existed for at least the last 2,700 years, as tolls had to be paid by travellers using the Susa–Babylon highway under the regime of Ashurbanipal, who reigned in the 7th century BC.[2] Aristotle and Pliny refer to tolls in Arabia and other parts of Asia. In India, before the 4th century BC, the Arthashastra notes the use of tolls. Germanic tribes charged tolls to travellers across mountain passes.

A 14th-century example (though not for a road) is Castle Loevestein in the Netherlands, which was built at a strategic point where two rivers meet. River tolls were charged on boats sailing along the river. The Øresund in Scandinavia was once subject to a toll to the Danish Monarch, which once provided a sizable portion of the king's revenue.

Many modern European roads were originally constructed as toll roads in order to recoup the costs of construction, maintenance and as a source of tax money that is paid primarily by someone other than the local residents. In 14th-century England, some of the most heavily used roads were repaired with money raised from tolls by pavage grants. Widespread toll roads sometimes restricted traffic so much, by their high tolls, that they interfered with trade and cheap transportation needed to alleviate local famines or shortages.[3]

Tolls were used in the Holy Roman Empire in the 14th and 15th centuries.

Industrialisation in Europe needed major improvements to the transport infrastructure which included many new or substantially improved roads, financed from tolls. The A5 road in Britain was built to provide a robust transport link between Britain and Ireland and had a toll house every few miles.

In the 20th century, road tolls were introduced in Europe to finance the construction of motorway networks and specific transport infrastructure such as bridges and tunnels. Italy was the first European country to charge motorway tolls, on a 50 km motorway section near Milan in 1924. It was followed by Greece, which made users pay for the network of motorways around and between its cities in 1927. Later in the 1950s and 1960s, France, Spain and Portugal started to build motorways largely with the aid of concessions, allowing rapid development of this infrastructure without massive State debts. Since then, road tolls have been introduced in the majority of the EU Member States.[4]

In the United States, prior to the introduction of the Interstate Highway System and the large federal grants supplied to states to build it, many states constructed their first controlled-access highways by floating bonds backed by toll revenues. Starting with the Pennsylvania Turnpike in 1940, and followed by similar roads in New Jersey (Garden State Parkway (1946) and New Jersey Turnpike, 1952), New York (New York State Thruway, 1954), Massachusetts (Massachusetts Turnpike, 1957), and others, numerous states throughout the 1950s established major toll roads. With the establishment of the Interstate Highway System in the late 1950s, toll road construction in the U.S. slowed down considerably, as the federal government now provided the bulk of funding to construct new freeways, and regulations required that such Interstate highways be free from tolls. Many older toll roads were added to the Interstate System under a grandfather clause that allowed tolls to continue to be collected on toll roads that predated the system. Some of these such as the Connecticut Turnpike and the Richmond–Petersburg Turnpike later removed their tolls when the initial bonds were paid off. Many states, however, have maintained the tolling of these roads, however, as a consistent source of revenue.

As the Interstate Highway System approached completion during the 1980s, states began constructing toll roads again to provide new controlled-access highways which were not part of the original interstate system funding. Houston's outer beltway of interconnected toll roads began in 1983, and many states followed over the last two decades of the 20th century adding new toll roads, including the tollway system around Orlando, Florida, Colorado's E-470, and Georgia State Route 400.

London, in an effort to reduce traffic within the city, instituted the London congestion charge in 2003, effectively making all roads within the city tolled.

In the United States, as states looked for ways to construct new freeways without federal funding again, to raise revenue for continued road maintenance, and to control congestion, new toll road construction saw significant increases during the first two decades of the 21st century. Spurred on by two innovations, the electronic toll collection system, and the advent of high occupancy and express lane tolls, many areas of the U.S saw large road building projects in major urban areas. Electronic toll collection, first introduced in the 1980s, reduces operating costs by removing toll collectors from roads. Tolled express lanes, by which certain lanes of a freeway are designated "toll only", increases revenue by allowing a free-to-use highway collect revenue by allowing drivers to bypass traffic jams by paying a toll. The E-ZPass system, compatible with many state systems, is the largest ETC system in the U.S., and is used for both fully tolled highways and tolled express lanes. Maryland Route 200 and the Triangle Expressway in North Carolina were the first toll roads built without toll booths, with drivers charged via ETC or by optical license plate recognition and are billed by mail.

19th-century toll booth in Brooklyn, New York Toll bar in Romania, 1877 Plaque commemorating the suppression of toll on a York bridge in 1914. Main article: Toll roads in Great Britain

Turnpike trusts were established in England and Wales from about 1706 in response to the need for better roads than the few and poorly-maintained tracks then available. Turnpike trusts were set up by individual Acts of Parliament, with powers to collect road tolls to repay loans for building, improving, and maintaining the principal roads in Britain. At their peak, in the 1830s, over 1,000 trusts[5] administered around 30,000 miles (48,000 km) of turnpike road in England and Wales, taking tolls at almost 8,000 toll-gates.[6] The trusts were ultimately responsible for the maintenance and improvement of most of the main roads in England and Wales, which were used to distribute agricultural and industrial goods economically. The tolls were a source of revenue for road building and maintenance, paid for by road users and not from general taxation. The turnpike trusts were gradually abolished from the 1870s. Most trusts improved existing roads, but some new roads, usually only short stretches, were also built. Thomas Telford's Holyhead road followed Watling Street from London but was exceptional in creating a largely new route beyond Shrewsbury, and especially beyond Llangollen. Built in the early 19th century, with many toll booths along its length, most of it is now the A5. In the modern day, one major toll road is the M6 Toll, relieving traffic congestion on the M6 in Birmingham. A few notable bridges and tunnels continue as toll roads including the Severn Bridge, the Dartford Crossing and Mersey Gateway bridge.

Some cities in Canada had toll roads in the 19th century. Roads radiating from Toronto required users to pay at toll gates along the street (Yonge Street, Bloor Street, Davenport Road, Kingston Road)[7] and disappeared after 1895.[8]

19th-century plank roads were usually operated as toll roads. One of the first U.S. motor roads, the Long Island Motor Parkway (which opened on October 10, 1908) was built by William Kissam Vanderbilt II, the great-grandson of Cornelius Vanderbilt. The road was closed in 1938 when it was taken over by the state of New York in lieu of back taxes.[9][10]

Main article: Road pricing

Road tolls were levied traditionally for a specific access (e.g. city) or for a specific infrastructure (e.g. roads, bridges). These concepts were widely used until the last century. However, the evolution in technology made it possible to implement road tolling policies based on different concepts. The different charging concepts are designed to suit different requirements regarding purpose of the charge, charging policy, the network to the charge, tariff class differentiation etc.:[11]

Time Based Charges and Access Fees: In a time-based charging regime, a road user has to pay for a given period of time in which they may use the associated infrastructure. For the practically identical access fees, the user pays for the access to a restricted zone for a period or several days.

Motorway and other Infrastructure Tolling: The term tolling is used for charging a well-defined special and comparatively costly infrastructure, like a bridge, a tunnel, a mountain pass, a motorway concession or the whole motorway network of a country. Classically a toll is due when a vehicle passes a tolling station, be it a manual barrier-controlled toll plaza or a free-flow multi-lane station.

Distance or Area Charging: In a distance or area charging system concept, vehicles are charged per total distance driven in a defined area.

Some toll roads charge a toll in only one direction. Examples include the Sydney Harbour Bridge, Sydney Harbour Tunnel and Eastern Distributor (these all charge tolls city-bound) in Australia, the Severn Bridges where the M4 and M48 in Great Britain crosses the River Severn, in the United States, crossings between Pennsylvania and New Jersey operated by Delaware River Port Authority and crossings between New Jersey and New York operated by Port Authority of New York and New Jersey.This technique is practical where the detour to avoid the toll is large or the toll differences are small.

.

Balintawak toll plaza of the North Luzon Expressway in Caloocan, Philippines. The toll barrier has both electronic toll collection and cash payment in the same barrier, before a new toll plaza was added. Tipo toll plaza in Subic–Clark–Tarlac Expressway, Hermosa, Bataan The open road tolling lanes at the West 163rd Street toll plaza, on the Tri-State Tollway near Markham, Illinois, United States

.

Overhead cameras and reader attach to gantry on Highway 407 in Ontario. See also: Electronic toll collection

Traditionally tolls were paid by hand at a toll gate. Although payments may still be made in cash, it is more common now to pay by credit card, by pre-paid card,[citation needed] or by an electronic toll collection system. In some places, payment is made using stickers which are affixed to the windscreen.

Three systems of toll roads exist: open (with mainline barrier toll plazas); closed (with entry/exit tolls) and open road (no toll booths, only electronic toll collection gantries at entrances and exits, or at strategic locations on the mainline of the road). Modern toll roads often use a combination of the three, with various entry and exit tolls supplemented by occasional mainline tolls: for example the Pennsylvania Turnpike and the New York State Thruway implement both systems in different sections.

On an open toll system, all vehicles stop at various locations along the highway to pay a toll. (Not to be confused with "open road tolling", where no vehicles stop to pay toll.) While this may save money from the lack of need to construct toll booths at every exit, it can cause traffic congestion while traffic queues at the mainline toll plazas (toll barriers). It is also possible for motorists to enter an 'open toll road' after one toll barrier and exit before the next one, thus travelling on the toll road toll-free. Most open toll roads have ramp tolls or partial access junctions to prevent this practice, known in the U.S. as "shunpiking".

With a closed system, vehicles collect a ticket when entering the highway. In some cases, the ticket displays the toll to be paid on exit. Upon exit, the driver must pay the amount listed for the given exit. Should the ticket be lost, a driver must typically pay the maximum amount possible for travel on that highway. Short toll roads with no intermediate entries or exits may have only one toll plaza at one end, with motorists traveling in either direction paying a flat fee either when they enter or when they exit the toll road. In a variant of the closed toll system, mainline barriers are present at the two endpoints of the toll road, and each interchange has a ramp toll that is paid upon exit or entry. In this case, a motorist pays a flat fee at the ramp toll and another flat fee at the end of the toll road; no ticket is necessary. In addition, with most systems, motorists may pay tolls only with cash and/or change; debit and credit cards are not accepted. However, some toll roads may have travel plazas with ATMs so motorists can stop and withdraw cash for the tolls.

The toll is calculated by the distance travelled on the toll road or the specific exit chosen. In the United States, for instance, the Kansas Turnpike, Ohio Turnpike, Pennsylvania Turnpike, New Jersey Turnpike, most of the Indiana Toll Road, New York State Thruway, and Florida's Turnpike currently implement closed systems.

The Union Toll Plaza on the Garden State Parkway was the first ever to use an automated toll collection machine. A plaque commemorating the event includes the first quarter collected at its toll booths.[12]

The first major deployment of an RFID electronic toll collection system in the United States was on the Dallas North Tollway in 1989 by Amtech (see TollTag). The Amtech RFID technology used on the Dallas North Tollway was originally developed at Sandia Labs for use in tagging and tracking livestock. In the same year, the Telepass active transponder RFID system was introduced across Italy.

Highway 407 in the province of Ontario, Canada, has no toll booths, and instead reads a transponder mounted on the windshields of each vehicle using the road (the rear licence plates of vehicles lacking a transponder are photographed when they enter and exit the highway). This made the highway the first all-automated toll highway in the world. A bill is mailed monthly for usage of the 407. Lower charges are levied on frequent 407 users who carry electronic transponders in their vehicles. The approach has not been without controversy: In 2003 the 407 ETR settled[13] a class action with a refund to users.

Throughout most of the East Coast of the United States, E-ZPass (operated under the brand I-Pass in Illinois) is accepted on almost all toll roads. Similar systems include SunPass in Florida, FasTrak in California, Good to Go in Washington State, and ExpressToll in Colorado. The systems use a small radio transponder mounted in or on a customer's vehicle to deduct toll fares from a pre-paid account as the vehicle passes through the toll barrier. This reduces manpower at toll booths and increases traffic flow and fuel efficiency by reducing the need for complete stops to pay tolls at these locations.

E-ZPass lanes at a New Jersey Turnpike (I-95) Toll Gate for Exit 8A in Monroe Township, New Jersey, United States

By designing a tollgate specifically for electronic collection, it is possible to carry out open-road tolling, where the customer does not need to slow at all when passing through the tollgate. The U.S. state of Texas is testing a system on a stretch of Texas 121 that has no toll booths. Drivers without a TollTag have their license plate photographed automatically and the registered owner will receive a monthly bill, at a higher rate than those vehicles with TollTags.[14]

The first all-electric toll road in the eastern United States, the InterCounty Connector (Maryland Route 200) was partially opened to traffic in February 2011,[15] and the final segment was completed in November 2014.[16] The first section of another all-electronic toll road, the Triangle Expressway, opened at the beginning of 2012 in North Carolina.[17]

Some toll roads are managed under such systems as the Build-Operate-Transfer (BOT) system. Private companies build the roads and are given a limited franchise. Ownership is transferred to the government when the franchise expires. This type of arrangement is prevalent in Australia, Canada, Hong Kong, India, South Korea, Japan and the Philippines. The BOT system is a fairly new concept that is gaining ground in the United States, with California, Delaware, Florida, Illinois, Indiana, Mississippi,[18] Texas, and Virginia already building and operating toll roads under this scheme. Pennsylvania, Massachusetts, New Jersey, and Tennessee are also considering the BOT methodology for future highway projects.

The more traditional means of managing toll roads in the United States is through semi-autonomous public authorities. Kansas, Maryland, Massachusetts, New Hampshire, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, and West Virginia manage their toll roads in this manner. While most of the toll roads in California, Delaware, Florida, Texas, and Virginia are operating under the BOT arrangement, a few of the older toll roads in these states are still operated by public authorities.

In France, all toll roads are operated by private companies, and the government takes a part of their profit.[citation needed]

Toll roads have been criticized as being inefficient in various ways:[19]

  1. They require vehicles to stop or slow down (except open road tolling); manual toll collection wastes time and raises vehicle operating costs.
  2. Collection costs can absorb up to one-third of revenues, and revenue theft is considered to be comparatively easy.
  3. Where the tolled roads are less congested than the parallel "free" roads, the traffic diversion resulting from the tolls increases congestion on the road system and reduces its usefulness.
  4. By tracking the vehicle locations, their drivers are subject to an effectual restriction of their freedom of movement and freedom from excessive surveillance.

A number of additional criticisms are also directed at toll roads in general:

  1. Toll roads are a form of regressive taxation; that is, compared to conventional taxes for funding roads, they benefit wealthier citizens more than poor citizens.[20][21]
  2. If toll roads are owned or managed by private entities, the citizens may lose money overall compared to conventional public funding because the private owners/operators of the toll system will naturally seek to profit from the roads.[22]
  3. The managing entities, whether public or private, may not correctly account for the overall social costs, particularly to the poor, when setting pricing and thus may hurt the neediest segments of society.[23]
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For other uses, see Asphalt (disambiguation). Note: The terms bitumen and asphalt are mostly interchangeable, Contractors Asphalt in Bryanston except where asphalt is used as a shorthand for asphalt concrete. Natural bitumen from the Dead Sea Refined asphalt The University of Queensland pitch drop experiment, demonstrating the viscosity of asphalt

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Asphalt (/ˈæsˌfɔːlt, -ˌfɑːlt/), also known as bitumen (UK English: /ˈbɪtʃəmən, ˈbɪtjʊmən/,[1] US English: /bɪˈt(j)uːmən, baɪˈt(j)uːmən/)[2] is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used.

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The primary use (70%) of asphalt Asphalt Road Construction Companies is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.

The terms “asphalt” and “bitumen” are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, “asphalt” (or “asphalt cement”) is commonly used for a refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called “bitumen”, and geologists worldwide often prefer the term for the naturally occurring variety. Common colloquial usage often refers to various forms of asphalt as “tar”, as in the name of the La Brea Tar Pits.

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Naturally occurring asphalt is sometimes specified by the term “crude bitumen”. Contractors Asphalt Its viscosity is similar to that of cold molasses[6][7] while the material obtained from the fractional distillation of crude oil boiling at 525 °C (977 °F) is sometimes referred to as “refined bitumen”. The Canadian province of Alberta has most of the world’s reserves of natural asphalt in the Athabasca oil sands, which cover 142,000 square kilometres (55,000 sq mi), an area larger than England.

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The word “asphalt” is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word meaning “asphalt/bitumen/pitch” which perhaps derives from ἀ-, “without” and σφάλλω (sfallō), “make fall”.  Asphalt Sealcoating Companies the first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall.[11] From the Greek, the word passed into late Latin, and thence into French (asphalte) and English (“asphaltum” and “asphalt”). In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the “asphaltic concrete” used to pave roads.

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The expression “bitumen” originated in the Sanskrit words jatu, meaning “pitch”, and jatu-krit, meaning “pitch creating” or “pitch producing” (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally gwitu-men (pertaining to pitch), and by others, pixtumens (exuding or bubbling pitch), which was subsequently shortened to bitumen, thence passing via French into English. From the same root is derived the Anglo-Saxon word cwidu (mastix), the German word Kitt (cement or mastic) and the old Norse word kvada.

In British English, “bitumen” is used instead of “asphalt”. The word “asphalt” is instead used to refer to asphalt concrete, a mixture of construction aggregate and asphalt itself (also called “tarmac” in common parlance). Bitumen mixed with clay was usually called “asphaltum”,[13] but the term is less commonly used today.[citation needed]

Alley

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In Australian English, “bitumen” is often used as the generic term for road surfaces.

In American English, “asphalt” is equivalent to the British “bitumen”. However, “asphalt” is also commonly used as a shortened form of “asphalt concrete” (therefore equivalent to the British “asphalt” or “tarmac”).

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In Canadian English, the word “bitumen” is used to refer to the vast Canadian deposits of extremely heavy crude oil,[14] while “asphalt” is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as “dilbit” in the Canadian petroleum industry, while bitumen “upgraded” to synthetic crude oil is known as “syncrude”, and syncrude blended with bitumen is called “synbit”.[15]

“Bitumen” is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. “Bituminous rock” is a form of sandstone impregnated with bitumen. The tar sands of Alberta, Canada are a similar material.

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Neither of the terms “asphalt” or “bitumen” should be confused with tar or coal tars.[further explanation needed]

See also: Asphaltene

The components of asphalt include four main classes of compounds:

The naphthene aromatics and polar aromatics are typically the majority components. Most natural bitumens also contain organosulfur compounds, resulting in an overall sulfur content of up to 4%. Nickel and vanadium are found at <10 parts per million, as is typical of some petroleum.

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The substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase.[16] “It is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large”.

Asphalt may be confused with coal tar, which is a visually similar black, thermoplastic material produced by the destructive distillation of coal. During the early and mid-20th century, when town gas was produced, coal tar was a readily available byproduct and extensively used as the binder for road aggregates. The addition of coal tar to macadam roads led to the word “tarmac”, which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, asphalt has completely overtaken the use of coal tar in these applications. Other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. “Pitch” is another term sometimes informally used at times to refer to asphalt, as in Pitch Lake.

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Bituminous outcrop of the Puy de la Poix, Clermont-Ferrand, France

The majority of asphalt used commercially is obtained from petroleum.[18] Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.

Natural deposits of bitumen include lakes such as the Pitch Lake in Trinidad and Tobago and Lake Bermudez in Venezuela. Natural seeps occur in the La Brea Tar Pits and in the Dead Sea.

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Bitumen also occurs in unconsolidated sandstones known as “oil sands” in Alberta, Canada, and the similar “tar sands” in Utah, US. The Canadian province of Alberta has most of the world’s reserves, in three huge deposits covering 142,000 square kilometres (55,000 sq mi), an area larger than England or New York state. These bituminous sands contain 166 billion barrels (26.4×10^9 m3) of commercially established oil reserves, giving Canada the third largest oil reserves in the world. Although historically it was used without refining to pave roads, nearly all of the output is now used as raw material for oil refineries in Canada and the United States.

Michigan left

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The world’s largest deposit of natural bitumen, known as the Athabasca oil sands, is located in the McMurray Formation of Northern Alberta. This formation is from the early Cretaceous, and is composed of numerous lenses of oil-bearing sand with up to 20% oil.[19] Isotopic studies show the oil deposits to be about 110 million years old.[20] Two smaller but still very large formations occur in the Peace River oil sands and the Cold Lake oil sands, to the west and southeast of the Athabasca oil sands, respectively. Of the Alberta deposits, only parts of the Athabasca oil sands are shallow enough to be suitable for surface mining. The other 80% has to be produced by oil wells using enhanced oil recovery techniques like steam-assisted gravity drainage.

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Much smaller heavy oil or bitumen deposits also occur in the Uinta Basin in Utah, US. The Tar Sand Triangle deposit, for example, is roughly 6% bitumen.

Bitumen may occur in hydrothermal veins. An example of this is within the Uinta Basin of Utah, in the US, where there is a swarm of laterally and vertically extensive veins composed of a solid hydrocarbon termed Gilsonite. These veins formed by the polymerization and solidification of hydrocarbons that were mobilized from the deeper oil shales of the Green River Formation during burial and diagenesis.

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Bitumen is similar to the organic matter in carbonaceous meteorites.[23] However, detailed studies have shown these materials to be distinct.[24] The vast Alberta bitumen resources are considered to have started out as living material from marine plants and animals, mainly algae, that died millions of years ago when an ancient ocean covered Alberta. They were covered by mud, buried deeply over time, and gently cooked into oil by geothermal heat at a temperature of 50 to 150 °C (120 to 300 °F). Due to pressure from the rising of the Rocky Mountains in southwestern Alberta, 80 to 55 million years ago, the oil was driven northeast hundreds of kilometres and trapped into underground sand deposits left behind by ancient river beds and ocean beaches, thus forming the oil sands.

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The use of natural bitumen for waterproofing, and as an adhesive dates at least to the fifth millennium BC, with a crop storage basket discovered in Mehrgarh, of the Indus Valley Civilization, lined with it.[25] By the 3rd millennia BC refined rock asphalt was in use, in the region, and was used to waterproof the Great Bath, Mohenjo-daro.

In the ancient Middle East, the Sumerians used natural bitumen deposits for mortar between bricks and stones, to cement parts of carvings, such as eyes, into place, for ship caulking, and for waterproofing.[3] The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon.

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The 1 kilometre (0.62 mi) long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis (ca. 800 BC) was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent.

Bitumen was used by ancient Egyptians to embalm mummies.[3][28] The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians’ primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake).

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Approximately 40 AD, Dioscorides described the Dead Sea material as Judaicum bitumen, and noted other places in the region where it could be found.[29] The Sidon bitumen is thought to refer to material found at Hasbeya.[30] Pliny refers also to bitumen being found in Epirus. It was a valuable strategic resource, the object of the first known battle for a hydrocarbon deposit—between the Seleucids and the Nabateans in 312 BC.

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In the ancient Far East, natural bitumen was slowly boiled to get rid of the higher fractions, leaving a thermoplastic material of higher molecular weight that when layered on objects became quite hard upon cooling. This was used to cover objects that needed waterproofing,[3] such as scabbards and other items. Statuettes of household deities were also cast with this type of material in Japan, and probably also in China.

In North America, archaeological recovery has indicated bitumen was sometimes used to adhere stone projectile points to wooden shafts.[32] In Canada, aboriginal people used bitumen seeping out of the banks of the Athabasca and other rivers to waterproof birch bark canoes, and also heated it in smudge pots to ward off mosquitoes in the summer.

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In 1553, Pierre Belon described in his work Observations that pissasphalto, a mixture of pitch and bitumen, was used in the Republic of Ragusa (now Dubrovnik, Croatia) for tarring of ships.

Road surface

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An 1838 edition of Mechanics Magazine cites an early use of asphalt in France. A pamphlet dated 1621, by “a certain Monsieur d’Eyrinys, states that he had discovered the existence (of asphaltum) in large quantities in the vicinity of Neufchatel”, and that he proposed to use it in a variety of ways – “principally in the construction of air-proof granaries, and in protecting, by means of the arches, the water-courses in the city of Paris from the intrusion of dirt and filth”, which at that time made the water unusable. “He expatiates also on the excellence of this material for forming level and durable terraces” in palaces, “the notion of forming such terraces in the streets not one likely to cross the brain of a Parisian of that generation”.

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But the substance was generally neglected in France until the revolution of 1830. In the 1830s there was a surge of interest, and asphalt became widely used “for pavements, flat roofs, and the lining of cisterns, and in England, some use of it had been made of it for similar purposes”. Its rise in Europe was “a sudden phenomenon”, after natural deposits were found “in France at Osbann (Bas-Rhin), the Parc (Ain) and the Puy-de-la-Poix (Puy-de-Dôme)”, although it could also be made artificially.[35] One of the earliest uses in France was the laying of about 24,000 square yards of Seyssel asphalt at the Place de la Concorde in 1835.

Among the earlier uses of bitumen in the United Kingdom was for etching. William Salmon’s Polygraphice (1673) provides a recipe for varnish used in etching, consisting of three ounces of virgin wax, two ounces of mastic, and one ounce of asphaltum.[37] By the fifth edition in 1685, he had included more asphaltum recipes from other sources.

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The first British patent for the use of asphalt was “Cassell’s patent asphalte or bitumen” in 1834.[35] Then on 25 November 1837, Richard Tappin Claridge patented the use of Seyssel asphalt (patent #7849), for use in asphalte pavement,[39][40] having seen it employed in France and Belgium when visiting with Frederick Walter Simms, who worked with him on the introduction of asphalt to Britain.[41][42] Dr T. Lamb Phipson writes that his father, Samuel Ryland Phipson, a friend of Claridge, was also “instrumental in introducing the asphalte pavement (in 1836)”.[43] Indeed, mastic pavements had been previously employed at Vauxhall by a competitor of Claridge, but without success.

Crocodile cracking

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Claridge obtained a patent in Scotland on 27 March 1838, and obtained a patent in Ireland on 23 April 1838. In 1851, extensions for the 1837 patent and for both 1838 patents were sought by the trustees of a company previously formed by Claridge. Claridge’s Patent Asphalte Company—formed in 1838 for the purpose of introducing to Britain “Asphalte in its natural state from the mine at Pyrimont Seysell in France”,—”laid one of the first asphalt pavements in Whitehall”.  Trials were made of the pavement in 1838 on the footway in Whitehall, the stable at Knightsbridge Barracks,”and subsequently on the space at the bottom of the steps leading from Waterloo Place to St. James Park”. “The formation in 1838 of Claridge’s Patent Asphalte Company (with a distinguished list of aristocratic patrons, and Marc and Isambard Brunel as, respectively, a trustee and consulting engineer), gave an enormous impetus to the development of a British asphalt industry”.[45] “By the end of 1838, at least two other companies, Robinson’s and the Bastenne company, were in production”,[50] with asphalt being laid as paving at Brighton, Herne Bay, Canterbury, Kensington, the Strand, and a large floor area in Bunhill-row, while meantime Claridge’s Whitehall paving “continue(d) in good order”.

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Asphalt Driveway Paving Price   (Redirected from Asphalt pavement) A road being resurfaced

A road surface or pavement is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past, gravel road surfaces, cobblestone and granite setts were extensively used, but these surfaces have mostly been replaced by asphalt or concrete laid on a compacted base course. Road surfaces are frequently marked to guide traffic. Today, permeable paving methods are beginning to be used for low-impact roadways and walkways. Pavements are crucial to countries such as US and Canada, which heavily depend on road transportation. Therefore, research projects such as Long-Term Pavement Performance are launched to optimize the life-cycle of different road surfaces.[1][2]

Red surfacing for the bicycle lane in the Netherlands

Closeup of asphalt on a driveway

Asphalt (specifically, asphalt concrete), sometimes called flexible pavement due to the nature in which it distributes loads, has been widely used since the 1920s. The viscous nature of the bitumen binder allows asphalt concrete to sustain significant plastic deformation, although fatigue from repeated loading over time is the most common failure mechanism. Most asphalt surfaces are laid on a gravel base, which is generally at least as thick as the asphalt layer, although some 'full depth' asphalt surfaces are laid directly on the native subgrade. In areas with very soft or expansive subgrades such as clay or peat, thick gravel bases or stabilization of the subgrade with Portland cement or lime may be required. Polypropylene and polyester geosynthetics have also been used for this purpose[3] and in some northern countries, a layer of polystyrene boards have been used to delay and minimize frost penetration into the subgrade.[4]

Depending on the temperature at which it is applied, asphalt is categorized as hot mix, warm mix, or cold mix. Hot mix asphalt is applied at temperatures over 300 °F (150 °C) with a free floating screed. Warm mix asphalt is applied at temperatures of 200–250 °F (95–120 °C), resulting in reduced energy usage and emissions of volatile organic compounds.[5] Cold mix asphalt is often used on lower-volume rural roads, where hot mix asphalt would cool too much on the long trip from the asphalt plant to the construction site.[6]

An asphalt concrete surface will generally be constructed for high-volume primary highways having an average annual daily traffic load greater than 1200 vehicles per day.[7] Advantages of asphalt roadways include relatively low noise, relatively low cost compared with other paving methods, and perceived ease of repair. Disadvantages include less durability than other paving methods, less tensile strength than concrete, the tendency to become slick and soft in hot weather and a certain amount of hydrocarbon pollution to soil and groundwater or waterways.

In the mid-1960s, rubberized asphalt was used for the first time, mixing crumb rubber from used tires with asphalt.[8] While a potential use for tires that would otherwise fill landfills and present a fire hazard, rubberized asphalt has shown greater incidence of wear in freeze-thaw cycles in temperate zones due to non-homogeneous expansion and contraction with non-rubber components. The application of rubberized asphalt is more temperature-sensitive, and in many locations can only be applied at certain times of the year.[citation needed]

Study results of the long-term acoustic benefits of rubberized asphalt are inconclusive. Initial application of rubberized asphalt may provide 3–5 decibels (dB) reduction in tire-pavement source noise emissions; however, this translates to only 1–3 decibels (dB) in total traffic noise level reduction (due to the other components of traffic noise). Compared to traditional passive attenuating measures (e.g., noise walls and earth berms), rubberized asphalt provides shorter-lasting and lesser acoustic benefits at typically much greater expense.[citation needed]

Concrete roadway in San Jose, California Further information: Concrete

Concrete surfaces (specifically, Portland cement concrete) are created using a concrete mix of Portland cement, coarse aggregate, sand and water. In virtually all modern mixes there will also be various admixtures added to increase workability, reduce the required amount of water, mitigate harmful chemical reactions and for other beneficial purposes. In many cases there will also be Portland cement substitutes added, such as fly ash. This can reduce the cost of the concrete and improve its physical properties. The material is applied in a freshly mixed slurry, and worked mechanically to compact the interior and force some of the cement slurry to the surface to produce a smoother, denser surface free from honeycombing. The water allows the mix to combine molecularly in a chemical reaction called hydration.

A concrete road in Ewing, New Jersey. The original pavement was laid in the 1950s and has not been significantly altered since.

Concrete surfaces have been refined into three common types: jointed plain (JPCP), jointed reinforced (JRCP) and continuously reinforced (CRCP). The one item that distinguishes each type is the jointing system used to control crack development.

One of the major advantages of concrete pavements is they are typically stronger and more durable than asphalt roadways. They also can be grooved to provide a durable skid-resistant surface. A notable disadvantage is that they typically can have a higher initial cost, and can be more time-consuming to construct. This cost can typically be offset through the long life cycle of the pavement. Concrete pavement can be maintained over time utilizing a series of methods known as concrete pavement restoration which include diamond grinding, dowel bar retrofits, joint and crack sealing, cross-stitching, etc. Diamond grinding is also useful in reducing noise and restoring skid resistance in older concrete pavement.[9][10]

The first street in the United States to be paved with concrete was Court Avenue in Bellefontaine, Ohio in 1893.[11][12] The first mile of concrete pavement in the United States was on Woodward Avenue in Detroit, Michigan in 1909.[13] Following these pioneering uses, the Lincoln Highway Association, established in October 1913 to oversee the creation of one of the United States' earliest east-west transcontinental highways for the then-new automobile, began to establish "seedling miles" of specifically concrete-paved roadbed in various places in the American Midwest, starting in 1914 west of Malta, Illinois, while using concrete with the specified concrete "ideal section" for the Lincoln Highway in Lake County, Indiana during 1922 and 1923.[14]

An example of composite pavement: hot-mix asphalt overlaid onto Portland cement concrete pavement

Composite pavements combine a Portland cement concrete sublayer with an asphalt. They are usually used to rehabilitate existing roadways rather than in new construction.

Asphalt overlays are sometimes laid over distressed concrete to restore a smooth wearing surface.[15] A disadvantage of this method is that movement in the joints between the underlying concrete slabs, whether from thermal expansion and contraction, or from deflection of the concrete slabs from truck axle loads, usually causes reflective cracks in the asphalt. To decrease reflective cracking, concrete pavement is broken apart through a break and seat, crack and seat, or rubblization process. Geosynthetics can be used for reflective crack control.[16] With break and seat and crack and seat processes, a heavy weight is dropped on the concrete to induce cracking, then a heavy roller is used to seat the resultant pieces into the subbase. The main difference between the two processes is the equipment used to break the concrete pavement and the size of the resulting pieces. The theory is frequent small cracks will spread thermal stress over a wider area than infrequent large joints, reducing the stress on the overlying asphalt pavement. Rubblization is a more complete fracturing of the old, worn-out concrete, effectively converting the old pavement into an aggregate base for a new asphalt road.[17]

Whitetopping uses Portland cement concrete to resurface a distressed asphalt road.

An asphalt milling machine in Boise, Idaho.

Distressed road materials can be reused when rehabilitating a roadway. The existing pavement is ground or broken up into small pieces, through a process called milling. It can then be transported to an asphalt or concrete plant and incorporated into new pavement, or recycled in place to form the base or subbase for new pavement. Some methods used include:

Main article: Chipseal

Bituminous surface treatment (BST) or chipseal is used mainly on low-traffic roads, but also as a sealing coat to rejuvenate an asphalt concrete pavement. It generally consists of aggregate spread over a sprayed-on asphalt emulsion or cut-back asphalt cement. The aggregate is then embedded into the asphalt by rolling it, typically with a rubber-tired roller. This type of surface is described by a wide variety of regional terms including "chip seal", "tar and chip", "oil and stone", "seal coat", "sprayed seal"[21] or "surface dressing"[22] or as simply "bitumen."

BST is used on hundreds of miles of the Alaska Highway and other similar roadways in Alaska, the Yukon Territory, and northern British Columbia. The ease of application of BST is one reason for its popularity, but another is its flexibility, which is important when roadways are laid down over unstable terrain that thaws and softens in the spring.

Other types of BSTs include micropaving, slurry seals and Novachip. These are laid down using specialized and proprietary equipment. They are most often used in urban areas where the roughness and loose stone associated with chip seals is considered undesirable.

A thin membrane surface (TMS) is an oil-treated aggregate which is laid down upon a gravel road bed, producing a dust-free road.[23] A TMS road reduces mud problems and provides stone-free roads for local residents where loaded truck traffic is negligible. The TMS layer adds no significant structural strength, and so is used on secondary highways with low traffic volume and minimal weight loading. Construction involves minimal subgrade preparation, following by covering with a 50-to-100-millimetre (2.0–3.9 in) cold mix asphalt aggregate.[7] The Operation Division of the Ministry of Highways and Infrastructure in Saskatchewan has the responsibility of maintaining 6,102 kilometres (3,792 mi) of thin membrane surface (TMS) highways.[24]

Otta seal is a low-cost road surface using a 16–30-millimetre (0.63–1.18 in) thick mixture of bitumen and crushed rock.[25]

Main article: Gravel road

Gravel is known to have been used extensively in the construction of roads by soldiers of the Roman Empire (see Roman road) but in 1998 a limestone-surfaced road, thought to date back to the Bronze Age, was found at Yarnton in Oxfordshire, Britain.[26] Applying gravel, or "metalling," has had two distinct usages in road surfacing. The term road metal refers to the broken stone or cinders used in the construction or repair of roads or railways,[27] and is derived from the Latin metallum, which means both "mine" and "quarry".[28] The term originally referred to the process of creating a gravel roadway. The route of the roadway would first be dug down several feet and, depending on local conditions, French drains may or may not have been added. Next, large stones were placed and compacted, followed by successive layers of smaller stones, until the road surface was composed of small stones compacted into a hard, durable surface. "Road metal" later became the name of stone chippings mixed with tar to form the road surfacing material tarmac. A road of such material is called a "metalled road" in Britain, a "paved road" in Canada and the US, or a "sealed road" in parts of Canada, Australia and New Zealand.[29]

A granular surface can be used with a traffic volume where the annual average daily traffic is 1,200 vehicles per day or less.[citation needed] There is some structural strength if the road surface combines a sub base and base and is topped with a double graded seal aggregate with emulsion.[7][30] Besides the 4,929 kilometres (3,063 mi) of granular pavements maintained in Saskatchewan, around 40% of New Zealand roads are unbound granular pavement structures.[24][31]

The decision whether to pave a gravel road or not often hinges on traffic volume. It has been found that maintenance costs for gravel roads often exceed the maintenance costs for paved or surface-treated roads when traffic volumes exceed 200 vehicles per day.[32]

Some communities are finding it makes sense to convert their low-volume paved roads to aggregate surfaces.[33]

Pavers (or paviours), generally in the form of pre-cast concrete blocks, are often used for aesthetic purposes, or sometimes at port facilities that see long-duration pavement loading. Pavers are rarely used in areas that see high-speed vehicle traffic.

Brick, cobblestone, sett, wood plank, and wood block pavements such as Nicolson pavement, were once common in urban areas throughout the world, but fell out of fashion in most countries, due to the high cost of labor required to lay and maintain them, and are typically only kept for historical or aesthetic reasons.[citation needed] In some countries, however, they are still common in local streets. In the Netherlands, brick paving has made something of a comeback since the adoption of a major nationwide traffic safety program in 1997. From 1998 through 2007, more than 41,000 km of city streets were converted to local access roads with a speed limit of 30 km/h, for the purpose of traffic calming.[34] One popular measure is to use brick paving - the noise and vibration slows motorists down. At the same time, it is not uncommon for cycle paths alongside a road to have a smoother surface than the road itself.[35][36]

Likewise, macadam and tarmac pavements can still sometimes[when?] be found buried underneath asphalt concrete or Portland cement concrete pavements, but are rarely[clarification needed] constructed today[when?].

There are also other methods and materials to create pavements that have appearance of brick pavements. The first method to create brick texture is to heat an asphalt pavement and use metal wires to imprint a brick pattern using a compactor to create stamped asphalt. A similar method is to use rubber imprinting tools to press over a thin layer of cement to create decorative concrete. Another method is to use a brick pattern stencil and apply a surfacing material over the stencil. Materials that can be applied to give the color of the brick and skid resistance can be in many forms. An example is to use colored polymer-modified concrete slurry which can be applied by screeding or spraying.[37] Another material is aggregate-reinforced thermoplastic which can be heat applied to the top layer of the brick-pattern surface.[38] Other coating materials over stamped asphalt are paints and two-part epoxy coating.[39]

Roadway surfacing choices are known to affect the intensity and spectrum of sound emanating from the tire/surface interaction.[40] Initial applications of noise studies occurred in the early 1970s. Noise phenomena are highly influenced by vehicle speed.

Roadway surface types contribute differential noise effects of up to 4 dB, with chip seal type and grooved roads being the loudest, and concrete surfaces without spacers being the quietest. Asphaltic surfaces perform intermediately relative to concrete and chip seal. Rubberized asphalt has been shown to give a marginal 3–5 dB reduction in tire-pavement noise emissions, and a marginally discernible 1–3 dB reduction in total road noise emissions when compared to conventional asphalt applications.

See also: Pothole, Crocodile cracking, Rut (roads), and Bleeding (roads) Deteriorating asphalt

As pavement systems primarily fail due to fatigue (in a manner similar to metals), the damage done to pavement increases with the fourth power of the axle load of the vehicles traveling on it. According to the AASHO Road Test, heavily loaded trucks can do more than 10,000 times the damage done by a normal passenger car. Tax rates for trucks are higher than those for cars in most countries for this reason, though they are not levied in proportion to the damage done.[41] Passenger cars are considered to have little practical effect on a pavement's service life, from a materials fatigue perspective.

Other failure modes include aging and surface abrasion. As years go by, the binder in a bituminous wearing course gets stiffer and less flexible. When it gets "old" enough, the surface will start losing aggregates, and macrotexture depth increases dramatically. If no maintenance action is done quickly on the wearing course, potholes will form. The freeze-thaw cycle in cold climates will dramatically accelerate pavement deterioration, once water can penetrate the surface.

If the road is still structurally sound, a bituminous surface treatment, such as a chipseal or surface dressing can prolong the life of the road at low cost. In areas with cold climate, studded tires may be allowed on passenger cars. In Sweden and Finland, studded passenger car tires account for a very large share of pavement rutting.

The physical properties of a stretch of pavement can be tested using a falling weight deflectometer.

Several design methods have been developed to determine the thickness and composition of road surfaces required to carry predicted traffic loads for a given period of time. Pavement design methods are continuously evolving. Among these are the Shell Pavement design method, and the American Association of State Highway and Transportation Officials (AASHTO) 1993 "Guide for Design of Pavement Structures". A new mechanistic-empirical design guide has been under development by NCHRP (Called Superpave Technology) since 1998. A new design guide called Mechanistic Empirical Pavement Design Guide (MEPDG) was developed and is about to be adopted by AASHTO.

Further research by University College London into pavements has led to the development of an indoor, 80-sq-metre artificial pavement at a research centre called Pedestrian Accessibility and Movement Environment Laboratory (PAMELA). It is used to simulate everyday scenarios, from different pavement users to varying pavement conditions.[42] There also exists a research facility near Auburn University, the NCAT Pavement Test Track, that is used to test experimental asphalt pavements for durability.

In addition to repair costs, the condition of a road surface has economic effects for road users. Rolling resistance increases on rough pavement, as does wear and tear of vehicle components. It has been estimated that poor road surfaces cost the average US driver $324 per year in vehicle repairs, or a total of $67 billion. Also, it has been estimated that small improvements in road surface conditions can decrease fuel consumption between 1.8 and 4.7%.[43]

Main article: Road surface marking

Road surface markings are used on paved roadways to provide guidance and information to drivers and pedestrians. It can be in the form of mechanical markers such as cat's eyes, botts' dots and rumble strips, or non-mechanical markers such as paints, thermoplastic, plastic and epoxy.

Permeable paving

Asphalt Surfacing Company Price Thru lanes indicated by arrows on California CR G4 (Montague Expressway) in Silicon Valley.

In the context of traffic control, a lane is part of a roadway (carriageway) that is designated for use by a single line of vehicles, to control and guide drivers and reduce traffic conflicts.[1] Most public roads (highways) have at least two lanes, one for traffic in each direction, separated by lane markings. On multilane roadways and busier two-lane roads, lanes are designated with road surface markings. Major highways often have two multi-lane roadways separated by a median.

Some roads and bridges that carry very low volumes of traffic are less than 15 feet (4.6 m) wide, and are only a single lane wide. Vehicles travelling in opposite directions must slow or stop to pass each other. In rural areas, these are often called country lanes. In urban areas, alleys are often only one lane wide. Urban and suburban one lane roads are often designated for one-way traffic.

Lane capacity varies widely due to conditions such as neighboring lanes, lane width, elements next to the road, number of driveways, presence of parking, speed limits, number of heavy vehicles and so on – the range can be as low as 1000 passenger cars / hour to as high as 4800 passenger cars /hour but mostly falls between 1500 and 2400 passenger cars / hour.[2]

The Ontario Highway 401 in the Greater Toronto area, with 17 travel lanes in 6 separate carriageways visible in the midground. Turning lane on the Rodovia BR-101 (Brazil) Play media Changing lanes, Gothenburg, Sweden Transfer lanes, connecting surface collector lanes with through lanes between two tunnels A left-turn merging lane in Germany, needing explanation by a crafted sign These usages lead to the phrases life in the slow lane and life in the fast lane, used to describe relaxed or busy lifestyles, respectively and used as the titles of various books and songs.

While in general, wider lanes are associated with a reduction in crashes,[7] in urban settings both narrow (less than 2.8 m) and wide (over 3.1~3.2 m) lanes increase crash risks.[8] Wider lanes (over 3.3~3.4m) are associated with 33% higher impact speeds, as well as higher crash rates. Carrying capacity is also maximal at a width of 3 to 3.1 metres (9.8 to 10.2 ft), both for motor traffic and for bicycles. Pedestrian volume declines as lanes widen, and intersections with narrower lanes provide the highest capacity for bicycles.[9] As lane width decreases, traffic speed diminishes.[10]

Advocates for safety of people walking and people on bikes, and many new urbanists disagree with traditional thinking in traffic engineering, saying that safety and capacity are not adversely impacted by reducing lanes widths to as little as 10 feet (3.0 m).[11] Moreover, wider travel lanes also increase exposure and crossing distance for pedestrians at intersections and midblock crossings.

assumed widths and heights in road design for Europe (in meters)

The widths of vehicle lanes typically vary from 9 to 15 feet (2.7 to 4.6 m). Lane widths are commonly narrower on low volume roads and wider on higher volume roads. The lane width depends on the assumed maximum vehicle width with an additional space to allow for lateral motion of the vehicle.

The maximum truck width had been 96 inches (2.438 m) in the Code of Federal Regulations of 1956 which matches with the width of eight-foot for shipping containers. This had been increased to 102 inches (2.591 m) in 1976 which explicitly states to be read as the slightly larger metric 2.6 metres (102.36 in) width respecting international harmonization.[12] The same applies to standards in Europe which had increased the allowable size of road vehicles with a current maximum of 2.55 metres (100.39 in) for most trucks and allowing 2.6 metres (102.36 in) for refrigerator trucks. The minimum extra space had been 0.20 metres (7.87 in) and it is currently assumed to be at least 0.25 metres (9.84 in) on each side. For roads with a lower amount of traffic it is allowed to build the second or third lane in the same direction to an assumed lower width for cars like 1.75 metres (68.90 in), however this is not recommended as a design principle for new roads as changes in the amount of traffic could make for unnecessarily increased risks in the future.

The Interstate Highway standards for the U.S. Interstate Highway System uses a 12-foot (3.7 m) standard for lane width, while narrower lanes are used on lower classification roads. In Europe, as laws and road width vary by country, the minimum widths of lanes is generally between 2.5 to 3.25 metres (8.2 to 10.7 ft).[13] The federal Bundesstraße interurban network in Germany defines a minimum of 3.5 metres (11 ft 6 in) for each lane for the smallest two lane roads with an additional 0.25 metres (9.84 in) on the outer sides and shoulders being at least 1.5 metres (59.06 in) on each side. A modern Autobahn divided highway will have two lanes per direction which are 3.75 metres (12 ft 4 in) wide with an additional clearance of 0.50 metres (19.69 in) on each side, while three lanes per direction are set at 3.75 metres (12 ft 4 in) for the rightmost lane and 3.5 metres (11 ft 6 in) for the other lanes. Urban access roads and roads in low-density areas may have lanes as small as 2.75 metres (9 ft 0 in) in width per lane with shoulders being at least 1 metre (3 ft 3 in) wide.[14]

Main article: Road surface marking A typical rural American freeway (Interstate 5 in the Central Valley of California). Notice the yellow line on the left, the dashed white line in the middle, and the solid white line on the right. Also note the rumble strip to the left of the yellow line.

Painted lane markings vary widely from country to country. In the United States, Canada, Mexico, Honduras, Puerto Rico, Virgin Islands and Norway, yellow lines separate traffic going opposite directions and white separates lanes of traffic traveling the same direction, but such is not the case in many European countries.

Lane markings are mostly lines painted on the road by a road marking machine, which can adjust the marking widths according to the lane type.[15]

Traffic reports in California often refer to accidents being "in the number X lane." The California Department of Transportation (Caltrans) assigns the numbers from left to right.[16] The far left passing lane is the number 1 lane. The number of the slow lane (closest to freeway onramps/offramps) depends on the total number of lanes, and could be anywhere from 2 to 8.

For much of human history, roads did not need lane markings because most people walked or rode horses at relatively slow speeds. Another reason for not using lane markings is that they are expensive to maintain.

When automobiles, trucks, and buses came into widespread use during the first two decades of the 20th century, head-on collisions became more common.

Without the guidance provided by lane markings, drivers in the early days often erred in favor of keeping closer to the middle of the road, rather than risk going off-road into ditches or trees[citation needed]. This practice often left inadequate room for opposing traffic.

The history of lane markings is connected to the mass automobile construction in Detroit. It resulted in the formation of the first Road Commission of Wayne County, Michigan in 1906 which was trying to make roads safer (Henry Ford served on the board in the first year).[17] The commission would order the construction of the first concrete road in 1909 (the Woodard Avenue in Detroit) and it conceived the centerline for highways in 1911. Hence the chairmen of the Road Commission, Edward N. Hines is widely credited as the inventor of line markings.[18]

The introduction as a common standard is connected to June McCarroll, a physician in Indio, California who started experimenting with painting lines on roads in 1917 after she was run off a highway by a truck driver. In November 1924, after years of lobbying by Dr. McCarroll and her allies, California officially adopted a policy of painting lines on its highways. A portion of Interstate 10 near Indio has been named the Dr. June McCarroll Memorial Freeway in her honor.

black center line on an Autobahn in Germany (late 1930s)

The first lane markings in Europe were painted at an accident hotspot in the small town of Sutton Coldfield near Birmingham, England in 1921. The success of this experiment made its way to other hotspots and later standardization of white paint for line markings in Great Britain.[19]

The first lane markings in Germany were used in Berlin in 1925 using white paint for line markings and road edge markings. When the standard for the new autobahn network was conceived in the 1930s it mandated the usage of black paint for the center line for each carriageway as black was better visible on the bright surface of the concrete roads.

By 1939, lane markings had become so popular that they were officially standardized throughout the United States. The concept of line markings spread throughout the world becoming standard for most roads. Originally the lines were drawn manually with normal paint which would bleach out quickly. After the war, the first machines for line markings were invented[20] and a plastic strip was becoming standard in the 1950s which led to gradually find line markings on all roads.

Main article: Right- and left-hand traffic Asphalt Contractors Near Me

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For other uses, see Asphalt (disambiguation). Note: The terms bitumen and asphalt are mostly interchangeable, Asphalt Contractor Magazine in Bryanston except where asphalt is used as a shorthand for asphalt concrete. Natural bitumen from the Dead Sea Refined asphalt The University of Queensland pitch drop experiment, demonstrating the viscosity of asphalt

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Asphalt (/ˈæsˌfɔːlt, -ˌfɑːlt/), also known as bitumen (UK English: /ˈbɪtʃəmən, ˈbɪtjʊmən/,[1] US English: /bɪˈt(j)uːmən, baɪˈt(j)uːmən/)[2] is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used.

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The primary use (70%) of asphalt Asphalt Driveway Sealing Contractors is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.

The terms “asphalt” and “bitumen” are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, “asphalt” (or “asphalt cement”) is commonly used for a refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called “bitumen”, and geologists worldwide often prefer the term for the naturally occurring variety. Common colloquial usage often refers to various forms of asphalt as “tar”, as in the name of the La Brea Tar Pits.

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Naturally occurring asphalt is sometimes specified by the term “crude bitumen”. Asphalt Contractor Magazine Its viscosity is similar to that of cold molasses[6][7] while the material obtained from the fractional distillation of crude oil boiling at 525 °C (977 °F) is sometimes referred to as “refined bitumen”. The Canadian province of Alberta has most of the world’s reserves of natural asphalt in the Athabasca oil sands, which cover 142,000 square kilometres (55,000 sq mi), an area larger than England.

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The word “asphalt” is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word meaning “asphalt/bitumen/pitch” which perhaps derives from ἀ-, “without” and σφάλλω (sfallō), “make fall”.  Asphalt And Paver Driveway the first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall.[11] From the Greek, the word passed into late Latin, and thence into French (asphalte) and English (“asphaltum” and “asphalt”). In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the “asphaltic concrete” used to pave roads.

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The expression “bitumen” originated in the Sanskrit words jatu, meaning “pitch”, and jatu-krit, meaning “pitch creating” or “pitch producing” (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally gwitu-men (pertaining to pitch), and by others, pixtumens (exuding or bubbling pitch), which was subsequently shortened to bitumen, thence passing via French into English. From the same root is derived the Anglo-Saxon word cwidu (mastix), the German word Kitt (cement or mastic) and the old Norse word kvada.

In British English, “bitumen” is used instead of “asphalt”. The word “asphalt” is instead used to refer to asphalt concrete, a mixture of construction aggregate and asphalt itself (also called “tarmac” in common parlance). Bitumen mixed with clay was usually called “asphaltum”,[13] but the term is less commonly used today.[citation needed]

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In Australian English, “bitumen” is often used as the generic term for road surfaces.

In American English, “asphalt” is equivalent to the British “bitumen”. However, “asphalt” is also commonly used as a shortened form of “asphalt concrete” (therefore equivalent to the British “asphalt” or “tarmac”).

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In Canadian English, the word “bitumen” is used to refer to the vast Canadian deposits of extremely heavy crude oil,[14] while “asphalt” is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as “dilbit” in the Canadian petroleum industry, while bitumen “upgraded” to synthetic crude oil is known as “syncrude”, and syncrude blended with bitumen is called “synbit”.[15]

“Bitumen” is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. “Bituminous rock” is a form of sandstone impregnated with bitumen. The tar sands of Alberta, Canada are a similar material.

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Neither of the terms “asphalt” or “bitumen” should be confused with tar or coal tars.[further explanation needed]

See also: Asphaltene

The components of asphalt include four main classes of compounds:

The naphthene aromatics and polar aromatics are typically the majority components. Most natural bitumens also contain organosulfur compounds, resulting in an overall sulfur content of up to 4%. Nickel and vanadium are found at <10 parts per million, as is typical of some petroleum.

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The substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase.[16] “It is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large”.

Asphalt may be confused with coal tar, which is a visually similar black, thermoplastic material produced by the destructive distillation of coal. During the early and mid-20th century, when town gas was produced, coal tar was a readily available byproduct and extensively used as the binder for road aggregates. The addition of coal tar to macadam roads led to the word “tarmac”, which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, asphalt has completely overtaken the use of coal tar in these applications. Other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. “Pitch” is another term sometimes informally used at times to refer to asphalt, as in Pitch Lake.

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Bituminous outcrop of the Puy de la Poix, Clermont-Ferrand, France

The majority of asphalt used commercially is obtained from petroleum.[18] Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.

Natural deposits of bitumen include lakes such as the Pitch Lake in Trinidad and Tobago and Lake Bermudez in Venezuela. Natural seeps occur in the La Brea Tar Pits and in the Dead Sea.

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Bitumen also occurs in unconsolidated sandstones known as “oil sands” in Alberta, Canada, and the similar “tar sands” in Utah, US. The Canadian province of Alberta has most of the world’s reserves, in three huge deposits covering 142,000 square kilometres (55,000 sq mi), an area larger than England or New York state. These bituminous sands contain 166 billion barrels (26.4×10^9 m3) of commercially established oil reserves, giving Canada the third largest oil reserves in the world. Although historically it was used without refining to pave roads, nearly all of the output is now used as raw material for oil refineries in Canada and the United States.

Asphalt concrete

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The world’s largest deposit of natural bitumen, known as the Athabasca oil sands, is located in the McMurray Formation of Northern Alberta. This formation is from the early Cretaceous, and is composed of numerous lenses of oil-bearing sand with up to 20% oil.[19] Isotopic studies show the oil deposits to be about 110 million years old.[20] Two smaller but still very large formations occur in the Peace River oil sands and the Cold Lake oil sands, to the west and southeast of the Athabasca oil sands, respectively. Of the Alberta deposits, only parts of the Athabasca oil sands are shallow enough to be suitable for surface mining. The other 80% has to be produced by oil wells using enhanced oil recovery techniques like steam-assisted gravity drainage.

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Much smaller heavy oil or bitumen deposits also occur in the Uinta Basin in Utah, US. The Tar Sand Triangle deposit, for example, is roughly 6% bitumen.

Bitumen may occur in hydrothermal veins. An example of this is within the Uinta Basin of Utah, in the US, where there is a swarm of laterally and vertically extensive veins composed of a solid hydrocarbon termed Gilsonite. These veins formed by the polymerization and solidification of hydrocarbons that were mobilized from the deeper oil shales of the Green River Formation during burial and diagenesis.

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Bitumen is similar to the organic matter in carbonaceous meteorites.[23] However, detailed studies have shown these materials to be distinct.[24] The vast Alberta bitumen resources are considered to have started out as living material from marine plants and animals, mainly algae, that died millions of years ago when an ancient ocean covered Alberta. They were covered by mud, buried deeply over time, and gently cooked into oil by geothermal heat at a temperature of 50 to 150 °C (120 to 300 °F). Due to pressure from the rising of the Rocky Mountains in southwestern Alberta, 80 to 55 million years ago, the oil was driven northeast hundreds of kilometres and trapped into underground sand deposits left behind by ancient river beds and ocean beaches, thus forming the oil sands.

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The use of natural bitumen for waterproofing, and as an adhesive dates at least to the fifth millennium BC, with a crop storage basket discovered in Mehrgarh, of the Indus Valley Civilization, lined with it.[25] By the 3rd millennia BC refined rock asphalt was in use, in the region, and was used to waterproof the Great Bath, Mohenjo-daro.

In the ancient Middle East, the Sumerians used natural bitumen deposits for mortar between bricks and stones, to cement parts of carvings, such as eyes, into place, for ship caulking, and for waterproofing.[3] The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon.

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The 1 kilometre (0.62 mi) long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis (ca. 800 BC) was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent.

Bitumen was used by ancient Egyptians to embalm mummies.[3][28] The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians’ primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake).

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Approximately 40 AD, Dioscorides described the Dead Sea material as Judaicum bitumen, and noted other places in the region where it could be found.[29] The Sidon bitumen is thought to refer to material found at Hasbeya.[30] Pliny refers also to bitumen being found in Epirus. It was a valuable strategic resource, the object of the first known battle for a hydrocarbon deposit—between the Seleucids and the Nabateans in 312 BC.

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In the ancient Far East, natural bitumen was slowly boiled to get rid of the higher fractions, leaving a thermoplastic material of higher molecular weight that when layered on objects became quite hard upon cooling. This was used to cover objects that needed waterproofing,[3] such as scabbards and other items. Statuettes of household deities were also cast with this type of material in Japan, and probably also in China.

In North America, archaeological recovery has indicated bitumen was sometimes used to adhere stone projectile points to wooden shafts.[32] In Canada, aboriginal people used bitumen seeping out of the banks of the Athabasca and other rivers to waterproof birch bark canoes, and also heated it in smudge pots to ward off mosquitoes in the summer.

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In 1553, Pierre Belon described in his work Observations that pissasphalto, a mixture of pitch and bitumen, was used in the Republic of Ragusa (now Dubrovnik, Croatia) for tarring of ships.

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An 1838 edition of Mechanics Magazine cites an early use of asphalt in France. A pamphlet dated 1621, by “a certain Monsieur d’Eyrinys, states that he had discovered the existence (of asphaltum) in large quantities in the vicinity of Neufchatel”, and that he proposed to use it in a variety of ways – “principally in the construction of air-proof granaries, and in protecting, by means of the arches, the water-courses in the city of Paris from the intrusion of dirt and filth”, which at that time made the water unusable. “He expatiates also on the excellence of this material for forming level and durable terraces” in palaces, “the notion of forming such terraces in the streets not one likely to cross the brain of a Parisian of that generation”.

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But the substance was generally neglected in France until the revolution of 1830. In the 1830s there was a surge of interest, and asphalt became widely used “for pavements, flat roofs, and the lining of cisterns, and in England, some use of it had been made of it for similar purposes”. Its rise in Europe was “a sudden phenomenon”, after natural deposits were found “in France at Osbann (Bas-Rhin), the Parc (Ain) and the Puy-de-la-Poix (Puy-de-Dôme)”, although it could also be made artificially.[35] One of the earliest uses in France was the laying of about 24,000 square yards of Seyssel asphalt at the Place de la Concorde in 1835.

Among the earlier uses of bitumen in the United Kingdom was for etching. William Salmon’s Polygraphice (1673) provides a recipe for varnish used in etching, consisting of three ounces of virgin wax, two ounces of mastic, and one ounce of asphaltum.[37] By the fifth edition in 1685, he had included more asphaltum recipes from other sources.

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The first British patent for the use of asphalt was “Cassell’s patent asphalte or bitumen” in 1834.[35] Then on 25 November 1837, Richard Tappin Claridge patented the use of Seyssel asphalt (patent #7849), for use in asphalte pavement,[39][40] having seen it employed in France and Belgium when visiting with Frederick Walter Simms, who worked with him on the introduction of asphalt to Britain.[41][42] Dr T. Lamb Phipson writes that his father, Samuel Ryland Phipson, a friend of Claridge, was also “instrumental in introducing the asphalte pavement (in 1836)”.[43] Indeed, mastic pavements had been previously employed at Vauxhall by a competitor of Claridge, but without success.

Asphalt

Asphalt Driveway Paving Price

Claridge obtained a patent in Scotland on 27 March 1838, and obtained a patent in Ireland on 23 April 1838. In 1851, extensions for the 1837 patent and for both 1838 patents were sought by the trustees of a company previously formed by Claridge. Claridge’s Patent Asphalte Company—formed in 1838 for the purpose of introducing to Britain “Asphalte in its natural state from the mine at Pyrimont Seysell in France”,—”laid one of the first asphalt pavements in Whitehall”.  Trials were made of the pavement in 1838 on the footway in Whitehall, the stable at Knightsbridge Barracks,”and subsequently on the space at the bottom of the steps leading from Waterloo Place to St. James Park”. “The formation in 1838 of Claridge’s Patent Asphalte Company (with a distinguished list of aristocratic patrons, and Marc and Isambard Brunel as, respectively, a trustee and consulting engineer), gave an enormous impetus to the development of a British asphalt industry”.[45] “By the end of 1838, at least two other companies, Robinson’s and the Bastenne company, were in production”,[50] with asphalt being laid as paving at Brighton, Herne Bay, Canterbury, Kensington, the Strand, and a large floor area in Bunhill-row, while meantime Claridge’s Whitehall paving “continue(d) in good order”.

Asphalt Contractor Magazine in Bryanston ?

Paver Repair Quotes For other uses, see Asphalt (disambiguation). Note: The terms bitumen and asphalt are mostly interchangeable, except where asphalt is used as a shorthand for asphalt concrete. Natural bitumen from the Dead Sea Refined asphalt The University of Queensland pitch drop experiment, demonstrating the viscosity of asphalt

Asphalt (/ˈæsˌfɔːlt, -ˌfɑːlt/), also known as bitumen (UK English: /ˈbɪəmən, ˈbɪtjʊmən/,[1] US English: /bɪˈt(j)mən, bˈt(j)mən/)[2] is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used.[3] The word is derived from the Ancient Greek ἄσφαλτος ásphaltos.[4]

The primary use (70%) of asphalt is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.[5]

The terms "asphalt" and "bitumen" are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, "asphalt" (or "asphalt cement") is commonly used for a refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called "bitumen", and geologists worldwide often prefer the term for the naturally occurring variety. Common colloquial usage often refers to various forms of asphalt as "tar", as in the name of the La Brea Tar Pits.

Naturally occurring asphalt is sometimes specified by the term "crude bitumen". Its viscosity is similar to that of cold molasses[6][7] while the material obtained from the fractional distillation of crude oil boiling at 525 °C (977 °F) is sometimes referred to as "refined bitumen". The Canadian province of Alberta has most of the world's reserves of natural asphalt in the Athabasca oil sands, which cover 142,000 square kilometres (55,000 sq mi), an area larger than England.[8]

The word "asphalt" is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word meaning "asphalt/bitumen/pitch",[9] which perhaps derives from ἀ-, "without" and σφάλλω (sfallō), "make fall".[10] The first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall.[11] From the Greek, the word passed into late Latin, and thence into French (asphalte) and English ("asphaltum" and "asphalt"). In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the "asphaltic concrete" used to pave roads.

The expression "bitumen" originated in the Sanskrit words jatu, meaning "pitch", and jatu-krit, meaning "pitch creating" or "pitch producing" (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally gwitu-men (pertaining to pitch), and by others, pixtumens (exuding or bubbling pitch), which was subsequently shortened to bitumen, thence passing via French into English. From the same root is derived the Anglo-Saxon word cwidu (mastix), the German word Kitt (cement or mastic) and the old Norse word kvada.[12]

In British English, "bitumen" is used instead of "asphalt". The word "asphalt" is instead used to refer to asphalt concrete, a mixture of construction aggregate and asphalt itself (also called "tarmac" in common parlance). Bitumen mixed with clay was usually called "asphaltum",[13] but the term is less commonly used today.[citation needed]

In Australian English, "bitumen" is often used as the generic term for road surfaces.

In American English, "asphalt" is equivalent to the British "bitumen". However, "asphalt" is also commonly used as a shortened form of "asphalt concrete" (therefore equivalent to the British "asphalt" or "tarmac").

In Canadian English, the word "bitumen" is used to refer to the vast Canadian deposits of extremely heavy crude oil,[14] while "asphalt" is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as "dilbit" in the Canadian petroleum industry, while bitumen "upgraded" to synthetic crude oil is known as "syncrude", and syncrude blended with bitumen is called "synbit".[15]

"Bitumen" is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. "Bituminous rock" is a form of sandstone impregnated with bitumen. The tar sands of Alberta, Canada are a similar material.

Neither of the terms "asphalt" or "bitumen" should be confused with tar or coal tars.[further explanation needed]

See also: Asphaltene

The components of asphalt include four main classes of compounds:

The naphthene aromatics and polar aromatics are typically the majority components. Most natural bitumens also contain organosulfur compounds, resulting in an overall sulfur content of up to 4%. Nickel and vanadium are found at <10 parts per million, as is typical of some petroleum.[5]

The substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase.[16] "It is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large".[17]

Asphalt may be confused with coal tar, which is a visually similar black, thermoplastic material produced by the destructive distillation of coal. During the early and mid-20th century, when town gas was produced, coal tar was a readily available byproduct and extensively used as the binder for road aggregates. The addition of coal tar to macadam roads led to the word "tarmac", which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, asphalt has completely overtaken the use of coal tar in these applications. Other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. "Pitch" is another term sometimes informally used at times to refer to asphalt, as in Pitch Lake.

Bituminous outcrop of the Puy de la Poix, Clermont-Ferrand, France

The majority of asphalt used commercially is obtained from petroleum.[18] Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.

Natural deposits of bitumen include lakes such as the Pitch Lake in Trinidad and Tobago and Lake Bermudez in Venezuela. Natural seeps occur in the La Brea Tar Pits and in the Dead Sea.

Bitumen also occurs in unconsolidated sandstones known as "oil sands" in Alberta, Canada, and the similar "tar sands" in Utah, US. The Canadian province of Alberta has most of the world's reserves, in three huge deposits covering 142,000 square kilometres (55,000 sq mi), an area larger than England or New York state. These bituminous sands contain 166 billion barrels (26.4×10^9 m3) of commercially established oil reserves, giving Canada the third largest oil reserves in the world. Although historically it was used without refining to pave roads, nearly all of the output is now used as raw material for oil refineries in Canada and the United States.[8]

The world's largest deposit of natural bitumen, known as the Athabasca oil sands, is located in the McMurray Formation of Northern Alberta. This formation is from the early Cretaceous, and is composed of numerous lenses of oil-bearing sand with up to 20% oil.[19] Isotopic studies show the oil deposits to be about 110 million years old.[20] Two smaller but still very large formations occur in the Peace River oil sands and the Cold Lake oil sands, to the west and southeast of the Athabasca oil sands, respectively. Of the Alberta deposits, only parts of the Athabasca oil sands are shallow enough to be suitable for surface mining. The other 80% has to be produced by oil wells using enhanced oil recovery techniques like steam-assisted gravity drainage.[21]

Much smaller heavy oil or bitumen deposits also occur in the Uinta Basin in Utah, US. The Tar Sand Triangle deposit, for example, is roughly 6% bitumen.[19]

Bitumen may occur in hydrothermal veins. An example of this is within the Uinta Basin of Utah, in the US, where there is a swarm of laterally and vertically extensive veins composed of a solid hydrocarbon termed Gilsonite. These veins formed by the polymerization and solidification of hydrocarbons that were mobilized from the deeper oil shales of the Green River Formation during burial and diagenesis.[22]

Bitumen is similar to the organic matter in carbonaceous meteorites.[23] However, detailed studies have shown these materials to be distinct.[24] The vast Alberta bitumen resources are considered to have started out as living material from marine plants and animals, mainly algae, that died millions of years ago when an ancient ocean covered Alberta. They were covered by mud, buried deeply over time, and gently cooked into oil by geothermal heat at a temperature of 50 to 150 °C (120 to 300 °F). Due to pressure from the rising of the Rocky Mountains in southwestern Alberta, 80 to 55 million years ago, the oil was driven northeast hundreds of kilometres and trapped into underground sand deposits left behind by ancient river beds and ocean beaches, thus forming the oil sands.[21]

The use of natural bitumen for waterproofing, and as an adhesive dates at least to the fifth millennium BC, with a crop storage basket discovered in Mehrgarh, of the Indus Valley Civilization, lined with it.[25] By the 3rd millennia BC refined rock asphalt was in use, in the region, and was used to waterproof the Great Bath, Mohenjo-daro.

In the ancient Middle East, the Sumerians used natural bitumen deposits for mortar between bricks and stones, to cement parts of carvings, such as eyes, into place, for ship caulking, and for waterproofing.[3] The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon.[26]

The 1 kilometre (0.62 mi) long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis (ca. 800 BC) was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent.[27]

Bitumen was used by ancient Egyptians to embalm mummies.[3][28] The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians' primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake).

Approximately 40 AD, Dioscorides described the Dead Sea material as Judaicum bitumen, and noted other places in the region where it could be found.[29] The Sidon bitumen is thought to refer to material found at Hasbeya.[30] Pliny refers also to bitumen being found in Epirus. It was a valuable strategic resource, the object of the first known battle for a hydrocarbon deposit—between the Seleucids and the Nabateans in 312 BC.[31]

In the ancient Far East, natural bitumen was slowly boiled to get rid of the higher fractions, leaving a thermoplastic material of higher molecular weight that when layered on objects became quite hard upon cooling. This was used to cover objects that needed waterproofing,[3] such as scabbards and other items. Statuettes of household deities were also cast with this type of material in Japan, and probably also in China.

In North America, archaeological recovery has indicated bitumen was sometimes used to adhere stone projectile points to wooden shafts.[32] In Canada, aboriginal people used bitumen seeping out of the banks of the Athabasca and other rivers to waterproof birch bark canoes, and also heated it in smudge pots to ward off mosquitoes in the summer.[21]

In 1553, Pierre Belon described in his work Observations that pissasphalto, a mixture of pitch and bitumen, was used in the Republic of Ragusa (now Dubrovnik, Croatia) for tarring of ships.[33]

An 1838 edition of Mechanics Magazine cites an early use of asphalt in France. A pamphlet dated 1621, by "a certain Monsieur d'Eyrinys, states that he had discovered the existence (of asphaltum) in large quantities in the vicinity of Neufchatel", and that he proposed to use it in a variety of ways – "principally in the construction of air-proof granaries, and in protecting, by means of the arches, the water-courses in the city of Paris from the intrusion of dirt and filth", which at that time made the water unusable. "He expatiates also on the excellence of this material for forming level and durable terraces" in palaces, "the notion of forming such terraces in the streets not one likely to cross the brain of a Parisian of that generation".[34]

But the substance was generally neglected in France until the revolution of 1830. In the 1830s there was a surge of interest, and asphalt became widely used "for pavements, flat roofs, and the lining of cisterns, and in England, some use of it had been made of it for similar purposes". Its rise in Europe was "a sudden phenomenon", after natural deposits were found "in France at Osbann (Bas-Rhin), the Parc (Ain) and the Puy-de-la-Poix (Puy-de-Dôme)", although it could also be made artificially.[35] One of the earliest uses in France was the laying of about 24,000 square yards of Seyssel asphalt at the Place de la Concorde in 1835.[36]

Among the earlier uses of bitumen in the United Kingdom was for etching. William Salmon's Polygraphice (1673) provides a recipe for varnish used in etching, consisting of three ounces of virgin wax, two ounces of mastic, and one ounce of asphaltum.[37] By the fifth edition in 1685, he had included more asphaltum recipes from other sources.[38]

The first British patent for the use of asphalt was "Cassell's patent asphalte or bitumen" in 1834.[35] Then on 25 November 1837, Richard Tappin Claridge patented the use of Seyssel asphalt (patent #7849), for use in asphalte pavement,[39][40] having seen it employed in France and Belgium when visiting with Frederick Walter Simms, who worked with him on the introduction of asphalt to Britain.[41][42] Dr T. Lamb Phipson writes that his father, Samuel Ryland Phipson, a friend of Claridge, was also "instrumental in introducing the asphalte pavement (in 1836)".[43] Indeed, mastic pavements had been previously employed at Vauxhall by a competitor of Claridge, but without success.[36]

Claridge obtained a patent in Scotland on 27 March 1838, and obtained a patent in Ireland on 23 April 1838. In 1851, extensions for the 1837 patent and for both 1838 patents were sought by the trustees of a company previously formed by Claridge.[35][44][45][46] Claridge's Patent Asphalte Company—formed in 1838 for the purpose of introducing to Britain "Asphalte in its natural state from the mine at Pyrimont Seysell in France",[47]—"laid one of the first asphalt pavements in Whitehall".[48] Trials were made of the pavement in 1838 on the footway in Whitehall, the stable at Knightsbridge Barracks,[47][49] "and subsequently on the space at the bottom of the steps leading from Waterloo Place to St. James Park".[49] "The formation in 1838 of Claridge's Patent Asphalte Company (with a distinguished list of aristocratic patrons, and Marc and Isambard Brunel as, respectively, a trustee and consulting engineer), gave an enormous impetus to the development of a British asphalt industry".[45] "By the end of 1838, at least two other companies, Robinson's and the Bastenne company, were in production",[50] with asphalt being laid as paving at Brighton, Herne Bay, Canterbury, Kensington, the Strand, and a large floor area in Bunhill-row, while meantime Claridge's Whitehall paving "continue(d) in good order".[51]

In 1838, there was a flurry of entrepreneurial activity involving asphalt, which had uses beyond paving. For example, asphalt could also be used for flooring, damp proofing in buildings, and for waterproofing of various types of pools and baths, both of which were also proliferating in the 19th century.[3][35][52] On the London stockmarket, there were various claims as to the exclusivity of asphalt quality from France, Germany and England. And numerous patents were granted in France, with similar numbers of patent applications being denied in England due to their similarity to each other. In England, "Claridge's was the type most used in the 1840s and 50s".[50]

In 1914, Claridge's Company entered into a joint venture to produce tar-bound macadam,[53] with materials manufactured through a subsidiary company called Clarmac Roads Ltd.[54] Two products resulted, namely Clarmac, and Clarphalte, with the former being manufactured by Clarmac Roads and the latter by Claridge's Patent Asphalte Co., although Clarmac was more widely used.[55][note 1] However, the First World War ruined the Clarmac Company, which entered into liquidation in 1915.[57][58] The failure of Clarmac Roads Ltd had a flow-on effect to Claridge's Company, which was itself compulsorily wound up,[59] ceasing operations in 1917,[60][61] having invested a substantial amount of funds into the new venture, both at the outset[59] and in a subsequent attempt to save the Clarmac Company.[57]

The first use of bitumen in the New World was by indigenous peoples. On the west coast, as early as the 13th century, the Tongva, Luiseño and Chumash peoples collected the naturally occurring bitumen that seeped to the surface above underlying petroleum deposits. All three groups used the substance as an adhesive. It is found on many different artifacts of tools and ceremonial items. For example, it was used on rattles to adhere gourds or turtle shells to rattle handles. It was also used in decorations. Small round shell beads were often set in asphaltum to provide decorations. It was used as a sealant on baskets to make them watertight for carrying water, possibly poisoning those who drank the water.[62] Asphalt was used also to seal the planks on ocean-going canoes.

Asphalt was first used to pave streets in the 1870s. At first naturally occurring "bituminous rock" was used, such as at Ritchie Mines in Macfarlan in Ritchie County, West Virginia from 1852 to 1873. In 1876, asphalt-based paving was used to pave Pennsylvania Avenue in Washington DC, in time for the celebration of the national centennial.[63] In the horse-drawn era, streets were unpaved and covered with dirt or gravel. However, that produced uneven wear, opened new hazards for pedestrians and made for dangerous potholes for bicycles and for motor vehicles. Manhattan alone had 130,000 horses in 1900, pulling streetcars, wagons, and carriages, and leaving their waste behind. They were not fast, and pedestrians could dodge and scramble their way across the crowded streets. Small towns continued to rely on dirt and gravel, but larger cities wanted much better streets. They looked to wood or granite blocks by the 1850s.[64] In 1890, a third of Chicago's 2000 miles of streets were paved, chiefly with wooden blocks, which gave better traction than mud. Brick surfacing was a good compromise, but even better was asphalt paving, which was easy to install and to cut through to get at sewers. With London and Paris serving as models, Washington laid 400,000 square yards of asphalt paving by 1882; it became the model for Buffalo, Philadelphia and elsewhere. By the end of the century, American cities boasted 30 million square yards of asphalt paving, well ahead of brick.[65] The streets became faster and more dangerous so electric traffic lights were installed. Electric trolleys (at 12 miles per hour) became the main transportation service for middle class shoppers and office workers until they bought automobiles after 1945 and commuted from more distant suburbs in privacy and comfort on asphalt highways.[66]

See also: Bitumount and History of the petroleum industry in Canada (oil sands and heavy oil)

Canada has the world's largest deposit of natural bitumen in the Athabasca oil sands, and Canadian First Nations along the Athabasca River had long used it to waterproof their canoes. In 1719, a Cree named Wa-Pa-Su brought a sample for trade to Henry Kelsey of the Hudson’s Bay Company, who was the first recorded European to see it. However, it wasn't until 1787 that fur trader and explorer Alexander MacKenzie saw the Athabasca oil sands and said, "At about 24 miles from the fork (of the Athabasca and Clearwater Rivers) are some bituminous fountains into which a pole of 20 feet long may be inserted without the least resistance."[21]

The value of the deposit was obvious from the start, but the means of extracting the bitumen was not. The nearest town, Fort McMurray, Alberta, was a small fur trading post, other markets were far away, and transportation costs were too high to ship the raw bituminous sand for paving. In 1915, Sidney Ells of the Federal Mines Branch experimented with separation techniques and used the product to pave 600 feet of road in Edmonton, Alberta. Other roads in Alberta were paved with material extracted from oil sands, but it was generally not economic. During the 1920s Dr. Karl A. Clark of the Alberta Research Council patented a hot water oil separation process and entrepreneur Robert C. Fitzsimmons[67] built the Bitumount oil separation plant, which between 1925 and 1958 produced up to 300 barrels (50 m3) per day of bitumen using Dr. Clark's method. Most of the bitumen was used for waterproofing roofs, but other uses included fuels, lubrication oils, printers ink, medicines, rust- and acid-proof paints, fireproof roofing, street paving, patent leather, and fence post preservatives.[21] Eventually Fitzsimmons ran out of money and the plant was taken over by the Alberta government. Today the Bitumount plant is a Provincial Historic Site.[68]

Bitumen was used in early photographic technology. In 1826 or 1827, it was used by French scientist Joseph Nicéphore Niépce to make the oldest surviving photograph from nature. The bitumen was thinly coated onto a pewter plate which was then exposed in a camera. Exposure to light hardened the bitumen and made it insoluble, so that when it was subsequently rinsed with a solvent only the sufficiently light-struck areas remained. Many hours of exposure in the camera were required, making bitumen impractical for ordinary photography, but from the 1850s to the 1920s it was in common use as a photoresist in the production of printing plates for various photomechanical printing processes.[69][70]

Bitumen was the nemesis of many artists during the 19th century. Although widely used for a time, it ultimately proved unstable for use in oil painting, especially when mixed with the most common diluents, such as linseed oil, varnish and turpentine. Unless thoroughly diluted, bitumen never fully solidifies and will in time corrupt the other pigments with which it comes into contact. The use of bitumen as a glaze to set in shadow or mixed with other colors to render a darker tone resulted in the eventual deterioration of many paintings, for instance those of Delacroix. Perhaps the most famous example of the destructiveness of bitumen is Théodore Géricault's Raft of the Medusa (1818–1819), where his use of bitumen caused the brilliant colors to degenerate into dark greens and blacks and the paint and canvas to buckle.[71]

The vast majority of refined asphalt is used in construction: primarily as a constituent of products used in paving and roofing applications. According to the requirements of the end use, asphalt is produced to specification. This is achieved either by refining or blending. It is estimated that the current world use of asphalt is approximately 102 million tonnes per year. Approximately 85% of all the asphalt produced is used as the binder in asphalt concrete for roads. It is also used in other paved areas such as airport runways, car parks and footways. Typically, the production of asphalt concrete involves mixing fine and coarse aggregates such as sand, gravel and crushed rock with asphalt, which acts as the binding agent. Other materials, such as recycled polymers (e.g., rubber tyres), may be added to the asphalt to modify its properties according to the application for which the asphalt is ultimately intended.

A further 10% of global asphalt production is used in roofing applications, where its waterproofing qualities are invaluable. The remaining 5% of asphalt is used mainly for sealing and insulating purposes in a variety of building materials, such as pipe coatings, carpet tile backing and paint. Asphalt is applied in the construction and maintenance of many structures, systems, and components, such as the following:

Main article: Asphalt concrete

The largest use of asphalt is for making asphalt concrete for road surfaces; this accounts for approximately 85% of the asphalt consumed in the United States. Asphalt concrete pavement mixes are typically composed of 5% asphalt cement and 95% aggregates (stone, sand, and gravel). Due to its highly viscous nature, asphalt cement must be heated so it can be mixed with the aggregates at the asphalt mixing facility. The temperature required varies depending upon characteristics of the asphalt and the aggregates, but warm-mix asphalt technologies allow producers to reduce the temperature required. There are about 4,000 asphalt concrete mixing plants in the US, and a similar number in Europe.[72]

When maintenance is performed on asphalt pavements, such as milling to remove a worn or damaged surface, the removed material can be returned to a facility for processing into new pavement mixtures. The asphalt in the removed material can be reactivated and put back to use in new pavement mixes.[73] With some 95% of paved roads being constructed of or surfaced with asphalt,[74] a substantial amount of asphalt pavement material is reclaimed each year. According to industry surveys conducted annually by the Federal Highway Administration and the National Asphalt Pavement Association, more than 99% of the asphalt removed each year from road surfaces during widening and resurfacing projects is reused as part of new pavements, roadbeds, shoulders and embankments.[75]

Asphalt concrete paving is widely used in airports around the world. Due to the sturdiness and ability to be repaired quickly, it is widely used for runways.

Further information: Fibre mastic asphalt

Mastic asphalt is a type of asphalt that differs from dense graded asphalt (asphalt concrete) in that it has a higher asphalt (binder) content, usually around 7–10% of the whole aggregate mix, as opposed to rolled asphalt concrete, which has only around 5% asphalt. This thermoplastic substance is widely used in the building industry for waterproofing flat roofs and tanking underground. Mastic asphalt is heated to a temperature of 210 °C (410 °F) and is spread in layers to form an impervious barrier about 20 millimeters (0.8 inches) thick.

A number of technologies allow asphalt to be mixed at much lower temperatures. These involve mixing with petroleum solvents to form "cutbacks" with reduced melting point or mixing with water to turn the asphalt into an emulsion. Asphalt emulsions contain up to 70% asphalt and typically less than 1.5% chemical additives. There are two main types of emulsions with different affinity for aggregates, cationic and anionic. Asphalt emulsions are used in a wide variety of applications. Chipseal involves spraying the road surface with asphalt emulsion followed by a layer of crushed rock, gravel or crushed slag. Slurry seal involves the creation of a mixture of asphalt emulsion and fine crushed aggregate that is spread on the surface of a road. Cold-mixed asphalt can also be made from asphalt emulsion to create pavements similar to hot-mixed asphalt, several inches in depth, and asphalt emulsions are also blended into recycled hot-mix asphalt to create low-cost pavements.

Main article: Synthetic crude oil See also: Petroleum production in Canada

Synthetic crude oil, also known as syncrude, is the output from a bitumen upgrader facility used in connection with oil sand production in Canada. Bituminous sands are mined using enormous (100 ton capacity) power shovels and loaded into even larger (400 ton capacity) dump trucks for movement to an upgrading facility. The process used to extract the bitumen from the sand is a hot water process originally developed by Dr. Karl Clark of the University of Alberta during the 1920s. After extraction from the sand, the bitumen is fed into a bitumen upgrader which converts it into a light crude oil equivalent. This synthetic substance is fluid enough to be transferred through conventional oil pipelines and can be fed into conventional oil refineries without any further treatment. By 2015 Canadian bitumen upgraders were producing over 1 million barrels (160×10^3 m3) per day of synthetic crude oil, of which 75% was exported to oil refineries in the United States.[76]

In Alberta, five bitumen upgraders produce synthetic crude oil and a variety of other products: The Suncor Energy upgrader near Fort McMurray, Alberta produces synthetic crude oil plus diesel fuel; the Syncrude Canada, Canadian Natural Resources, and Nexen upgraders near Fort McMurray produce synthetic crude oil; and the Shell Scotford Upgrader near Edmonton produces synthetic crude oil plus an intermediate feedstock for the nearby Shell Oil Refinery.[77] A sixth upgrader, under construction in 2015 near Redwater, Alberta, will upgrade half of its crude bitumen directly to diesel fuel, with the remainder of the output being sold as feedstock to nearby oil refineries and petrochemical plants.[78]

See also: Western Canadian Select

Canadian bitumen does not differ substantially from oils such as Venezuelan extra-heavy and Mexican heavy oil in chemical composition, and the real difficulty is moving the extremely viscous bitumen through oil pipelines to the refinery. Many modern oil refineries are extremely sophisticated and can process non-upgraded bitumen directly into products such as gasoline, diesel fuel, and refined asphalt without any preprocessing. This is particularly common in areas such as the US Gulf coast, where refineries were designed to process Venezuelan and Mexican oil, and in areas such as the US Midwest where refineries were rebuilt to process heavy oil as domestic light oil production declined. Given the choice, such heavy oil refineries usually prefer to buy bitumen rather than synthetic oil because the cost is lower, and in some cases because they prefer to produce more diesel fuel and less gasoline.[77] By 2015 Canadian production and exports of non-upgraded bitumen exceeded that of synthetic crude oil at over 1.3 million barrels (210×10^3 m3) per day, of which about 65% was exported to the United States.[76]

Because of the difficulty of moving crude bitumen through pipelines, non-upgraded bitumen is usually diluted with natural-gas condensate in a form called dilbit or with synthetic crude oil, called synbit. However, to meet international competition, much non-upgraded bitumen is now sold as a blend of multiple grades of bitumen, conventional crude oil, synthetic crude oil, and condensate in a standardized benchmark product such as Western Canadian Select. This sour, heavy crude oil blend is designed to have uniform refining characteristics to compete with internationally marketed heavy oils such as Mexican Mayan or Arabian Dubai Crude.[77]

Asphalt was used starting in the 1960s as an hydrophobic matrix aiming to encapsulate radioactive waste such as medium-activity salts (mainly soluble sodium nitrate and sodium sulfate) produced by the reprocessing of spent nuclear fuels or radioactive sludges from sedimentation ponds.[79][80] Bituminised radioactive waste containing highly radiotoxic alpha-emitting transuranic elements from nuclear reprocessing plants have been produced at industrial scale in France, Belgium and Japan, but this type of waste conditioning has been abandoned because operational safety issues (risks of fire, as occurred in a bituminisation plant at Tokai Works in Japan)[81][82] and long-term stability problems related to their geological disposal in deep rock formations. One of the main problem is the swelling of asphalt exposed to radiation and to water. Asphalt swelling is first induced by radiation because of the presence of hydrogen gas bubbles generated by alpha and gamma radiolysis.[83][84] A second mechanism is the matrix swelling when the encapsulated hygroscopic salts exposed to water or moisture start to rehydrate and to dissolve. The high concentration of salt in the pore solution inside the bituminised matrix is then responsible for osmotic effects inside the bituminised matrix. The water moves in the direction of the concentrated salts, the asphalt acting as a semi-permeable membrane. This also causes the matrix to swell. The swelling pressure due to osmotic effect under constant volume can be as high as 200 bar. If not properly managed, this high pressure can cause fractures in the near field of a disposal gallery of bituminised medium-level waste. When the bituminised matrix has been altered by swelling, encapsulated radionuclides are easily leached by the contact of ground water and released in the geosphere. The high ionic strength of the concentrated saline solution also favours the migration of radionuclides in clay host rocks. The presence of chemically reactive nitrate can also affect the redox conditions prevailing in the host rock by establishing oxidizing conditions, preventing the reduction of redox-sensitive radionuclides. Under their higher valences, radionuclides of elements such as selenium, technetium, uranium, neptunium and plutonium have a higher solubility and are also often present in water as non-retarded anions. This makes the disposal of medium-level bituminised waste very challenging.

Different type of asphalt have been used: blown bitumen (partly oxidized with air oxygen at high temperature after distillation, and harder) and direct distillation bitumen (softer). Blown bitumens like Mexphalte, with a high content of saturated hydrocarbons, are more easily biodegraded by microorganisms than direct distillation bitumen, with a low content of saturated hydrocarbons and a high content of aromatic hydrocarbons.[85]

Concrete encapsulation of radwaste is presently considered a safer alternative by the nuclear industry and the waste management organisations.

Roofing shingles account for most of the remaining asphalt consumption. Other uses include cattle sprays, fence-post treatments, and waterproofing for fabrics. Asphalt is used to make Japan black, a lacquer known especially for its use on iron and steel, and it is also used in paint and marker inks by some exterior paint supply companies to increase the weather resistance and permanence of the paint or ink, and to make the color darker.[86] Asphalt is also used to seal some alkaline batteries during the manufacturing process.

Typical asphalt plant for making asphalt

About 40,000,000 tons were produced in 1984.[needs update] It is obtained as the "heavy" (i.e., difficult to distill) fraction. Material with a boiling point greater than around 500 °C is considered asphalt. Vacuum distillation separates it from the other components in crude oil (such as naphtha, gasoline and diesel). The resulting material is typically further treated to extract small but valuable amounts of lubricants and to adjust the properties of the material to suit applications. In a de-asphalting unit, the crude asphalt is treated with either propane or butane in a supercritical phase to extract the lighter molecules, which are then separated. Further processing is possible by "blowing" the product: namely reacting it with oxygen. This step makes the product harder and more viscous.[5]

Asphalt is typically stored and transported at temperatures around 150 °C (302 °F). Sometimes diesel oil or kerosene are mixed in before shipping to retain liquidity; upon delivery, these lighter materials are separated out of the mixture. This mixture is often called "bitumen feedstock", or BFS. Some dump trucks route the hot engine exhaust through pipes in the dump body to keep the material warm. The backs of tippers carrying asphalt, as well as some handling equipment, are also commonly sprayed with a releasing agent before filling to aid release. Diesel oil is no longer used as a release agent due to environmental concerns.

Main article: Oil sands

Naturally occurring crude bitumen impregnated in sedimentary rock is the prime feed stock for petroleum production from "oil sands", currently under development in Alberta, Canada. Canada has most of the world's supply of natural bitumen, covering 140,000 square kilometres[14] (an area larger than England), giving it the second-largest proven oil reserves in the world. The Athabasca oil sands are the largest bitumen deposit in Canada and the only one accessible to surface mining, although recent technological breakthroughs have resulted in deeper deposits becoming producible by in situ methods. Because of oil price increases after 2003, producing bitumen became highly profitable, but as a result of the decline after 2014 it became uneconomic to build new plants again. By 2014, Canadian crude bitumen production averaged about 2.3 million barrels (370,000 m3) per day and was projected to rise to 4.4 million barrels (700,000 m3) per day by 2020.[15] The total amount of crude bitumen in Alberta that could be extracted is estimated to be about 310 billion barrels (50×10^9 m3),[8] which at a rate of 4,400,000 barrels per day (700,000 m3/d) would last about 200 years.

Main articles: Peak oil, Global warming, and Bioasphalt

Although uncompetitive economically, asphalt can be made from nonpetroleum-based renewable resources such as sugar, molasses and rice, corn and potato starches. Asphalt can also be made from waste material by fractional distillation of used motor oil, which is sometimes otherwise disposed of by burning or dumping into landfills. Use of motor oil may cause premature cracking in colder climates, resulting in roads that need to be repaved more frequently.[87]

Nonpetroleum-based asphalt binders can be made light-colored. Lighter-colored roads absorb less heat from solar radiation, reducing their contribution to the urban heat island effect.[88] Parking lots that use asphalt alternatives are called green parking lots.

Selenizza is a naturally occurring solid hydrocarbon bitumen found in native deposits in Selenice, in Albania, the only European asphalt mine still in use. The bitumen is found in the form of veins, filling cracks in a more or less horizontal direction. The bitumen content varies from 83% to 92% (soluble in carbon disulphide), with a penetration value near to zero and a softening point (ring and ball) around 120 °C. The insoluble matter, consisting mainly of silica ore, ranges from 8% to 17%.

Albanian bitumen extraction has a long history and was practiced in an organized way by the Romans. After centuries of silence, the first mentions of Albanian bitumen appeared only in 1868, when the Frenchman Coquand published the first geological description of the deposits of Albanian bitumen. In 1875, the exploitation rights were granted to the Ottoman government and in 1912, they were transferred to the Italian company Simsa. Since 1945, the mine was exploited by the Albanian government and from 2001 to date, the management passed to a French company, which organized the mining process for the manufacture of the natural bitumen on an industrial scale.[89]

Today the mine is predominantly exploited in an open pit quarry but several of the many underground mines (deep and extending over several km) still remain viable. Selenizza is produced primarily in granular form, after melting the bitumen pieces selected in the mine.

Selenizza[90] is mainly used as an additive in the road construction sector. It is mixed with traditional asphalt to improve both the viscoelastic properties and the resistance to ageing. It may be blended with the hot asphalt in tanks, but its granular form allows it to be fed in the mixer or in the recycling ring of normal asphalt plants. Other typical applications include the production of mastic asphalts for sidewalks, bridges, car-parks and urban roads as well as drilling fluid additives for the oil and gas industry. Selenizza is available in powder or in granular material of various particle sizes and is packaged in sacks or in thermal fusible polyethylene bags.

A life-cycle assessment study of the natural selenizza compared with petroleum asphalt has shown that the environmental impact of the selenizza is about half the impact of the road asphalt produced in oil refineries in terms of carbon dioxide emission.[91]

People can be exposed to asphalt in the workplace by breathing in fumes or skin absorption. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit of 5 mg/m3 over a 15-minute period.[92]

Asphalt is basically an inert material that must be heated or diluted to a point where it becomes workable for the production of materials for paving, roofing, and other applications. In examining the potential health hazards associated with asphalt, the International Agency for Research on Cancer (IARC) determined that it is the application parameters, predominantly temperature, that affect occupational exposure and the potential bioavailable carcinogenic hazard/risk of the asphalt emissions.[93] In particular, temperatures greater than 199 °C (390 °F), were shown to produce a greater exposure risk than when asphalt was heated to lower temperatures, such as those typically used in asphalt pavement mix production and placement.[94] IARC has classified asphalt as a Class 2B possible carcinogen.

An asphalt mixing plant for hot aggregate
  1. ^ "bitumen Meaning in the Cambridge English Dictionary". dictionary.cambridge.org. 
  2. ^ "American Heritage Dictionary". 
  3. ^ a b c d e Abraham, Herbert (1938). Asphalts and Allied Substances: Their Occurrence, Modes of Production, Uses in the Arts, and Methods of Testing (4th ed.). New York: D. Van Nostrand Co. Retrieved 16 November 2009.  Full text at Internet Archive (archive.org)
  4. ^ asphalt Archived 9 March 2016 at the Wayback Machine., Chambers 21st Century Dictionary
  5. ^ a b c Anja Sörensen and Bodo Wichert "Asphalt and Bitumen" in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2009. doi:10.1002/14356007.a03_169.pub2http://www.qrpoil.com/site/?bitumen
  6. ^ "Oil Sands – Glossary". Oil Sands Royalty Guidelines. Government of Alberta. 2008. Archived from the original on 1 November 2007. Retrieved 2 February 2008. 
  7. ^ Walker, Ian C. (1998), Marketing Challenges for Canadian Bitumen (PDF), Tulsa, OK: International Centre for Heavy Hydrocarbons, archived from the original (PDF) on 2012-03-13, Bitumen has been defined by various sources as crude oil with a dynamic viscosity at reservoir conditions of more than 10,000 centipoise. Canadian "bitumen" supply is more loosely accepted as production from the Athabasca, Wabasca, Peace River and Cold Lake oil-sands deposits. The majority of the oil produced from these deposits has an API gravity of between 8° and 12° and a reservoir viscosity of over 10,000 centipoise although small volumes have higher API gravities and lower viscosities. 
  8. ^ a b c "ST98-2015: Alberta's Energy Reserves 2014 and Supply/Demand Outlook 2015–2024" (PDF). Statistical Reports (ST). Alberta Energy Regulator. 2015. Retrieved 19 January 2016. 
  9. ^ ἄσφαλτος, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus
  10. ^ σφάλλω, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus
  11. ^ Herodotus, The Histories, 1.179.4, on Perseus
  12. ^ Abraham, Herbert (1938), p.1
  13. ^ Béguin, André. "A technical dictionary of printmaking – Bitumen". www.polymetaal.nl. Retrieved 27 January 2016. 
  14. ^ a b "What is Oil Sands". Alberta Energy. 2007. Archived from the original on 5 February 2016. Retrieved 10 January 2008. 
  15. ^ a b "2007 Canadian Crude Oil Forecast and Market Outlook". Canadian Association of Petroleum Producers. June 2007. Archived from the original on February 26, 2014. Retrieved 30 May 2008. 
  16. ^ Muhammad Abdul Quddus (1992). "Catalytic Oxidation of Asphalt". Thesis submitted to Department of Applied Chemistry; University of Karachi. Pakistan: Higher Education Commission Pakistan: Pakistan Research Repository. p. 6, in ch.2 pdf. Archived from the original on 5 February 2011. 
  17. ^ Muhammad Abdul Quddus (1992), p.99, in ch.5 pdf
  18. ^ Speight, James G. (2015). Asphalt Materials Science and Technology. Elsevier Science. p. 82. ISBN 978-0-12-800501-9. 
  19. ^ a b Bunger, J.; Thomas, K.; Dorrence, S. (1979). "Compound types and properties of Utah and Athabasca tar sand bitumens". Fuel. 58 (3): 183–195. doi:10.1016/0016-2361(79)90116-9. 
  20. ^ Selby, D.; Creaser, R. (2005). "Direct radiometric dating of hydrocarbon deposits using rhenium-osmium isotopes". Science. 308 (5726): 1293–1295. Bibcode:2005Sci...308.1293S. doi:10.1126/science.1111081. PMID 15919988. 
  21. ^ a b c d e "Facts about Alberta's oil sands and its industry" (PDF). Oil Sands Discovery Centre. Archived from the original (PDF) on 23 November 2015. Retrieved 19 January 2015. 
  22. ^ T. Boden and B. Tripp (2012). Gilsonite veins of the Uinta Basin, Utah. Utah, US: Utah Geological Survey, Special Study 141. 
  23. ^ Hayatsu; et al. Meteoritics. 18: 310. CS1 maint: Untitled periodical (link)
  24. ^ Kim; Yang. Journal of Astronomy and Space Sciences. 15 (1): 163–174. CS1 maint: Untitled periodical (link)
  25. ^ McIntosh, Jane. The Ancient Indus Valley. p. 57
  26. ^ Herodotus, Book I, 179
  27. ^ Abraham, Herbert (1920). Asphalts And Allied Substances. D. Van Nostrand. 
  28. ^ Pringle, Heather Anne (2001). The Mummy Congress: Science, Obsession, and the Everlasting Dead. New York, NY: Barnes & Noble Books. pp. 196–197. ISBN 0-7607-7151-0. 
  29. ^ Pedanius Dioscorides. De Materia Medica. . Original written ca. 40 AD, translated by Goodyer (1655) [1] or (Greek/Latin) compiled by Sprengel (1829) [2] p. 100 (p. 145 in PDF).
  30. ^ Connan, Jacques; Nissenbaum, Arie (2004). "The organic geochemistry of the Hasbeya asphalt (Lebanon): comparison with asphalts from the Dead Sea area and Iraq". Organic Geochemistry. 35 (6): 775–789. doi:10.1016/j.orggeochem.2004.01.015. ISSN 0146-6380. 
  31. ^ Arie Nissenbaum (May 1978). "Dead Sea Asphalts—Historical Aspects [free abstract]". AAPG Bulletin. 62 (5): 837–844. doi:10.1306/c1ea4e5f-16c9-11d7-8645000102c1865d. 
  32. ^ The Megalithic Portal and Megalith Map. "C.Michael Hogan (2008) ''Morro Creek'', ed. by A. Burnham". Megalithic.co.uk. Retrieved 27 August 2013. 
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  34. ^ "Nothing New under the Sun (on French asphaltum use in 1621)". The Mechanic's magazine, museum, register, journal and gazette. 29. London: W.A. Robertson. 7 April – 29 September 1838. p. 176. 
  35. ^ a b c d Miles, Lewis (2000). "Section 10.6: Damp Proofing". in Australian Building: A Cultural Investigation (PDF). p. 10.06.1. Archived from the original (PDF) on 15 December 2010. Retrieved 11 November 2009. . Note: different sections of Miles' online work were written in different years, as evidenced at the top of each page (not including the heading page of each section). This particular section appears to have been written in 2000
  36. ^ a b R.J. Forbes (1958), Studies in Early Petroleum History, Leiden, Netherlands: E.J. Brill, p. 24, retrieved 10 June 2010 
  37. ^ Salmon, William (1673). Polygraphice; Or, The Arts of Drawing, Engraving, Etching, Limning, Painting, Washing, Varnishing, Gilding, Colouring, Dying, Beautifying and Perfuming (Second ed.). London: R. Jones. p. 81. 
  38. ^ Salmon, William (1685), Polygraphice; Or, The Arts of Drawing, Engraving, Etching, Limning, Painting, Washing, Varnishing, Gilding, Colouring, Dying, Beautifying and Perfuming (5th ed.), London: R. Jones, pp. 76–77, retrieved 18 August 2010  Text at Internet Archive
  39. ^ "Specification of the Patent granted to Richard Tappin Claridge, of the County of Middlesex, for a Mastic Cement, or Composition applicable to Paving and Road making, covering Buildings and various purposes". Journal of the Franklin Institute of the State of Pennsylvania and Mechanics' Register. Vol. 22. London: Pergamon Press. July 1838. pp. 414–418. Retrieved 18 November 2009. 
  40. ^ "Comments on asphalt patents of R.T. Claridge, Esq". Notes and Queries: A medium of intercommunication for Literary Men, General Readers, etc. Ninth series. Volume XII, July–December, 1903 (9th S. XII, 4 July 1903). London: John C. Francis. 20 January 1904. pp. 18–19.  Writer is replying to note or query from previous publication, cited as 9th S. xi. 30
  41. ^ "Obituary of Frederick Walter Simms". Monthly Notices of the Royal Astronomical Society. London: Strangeways & Walden. XXVI: 120–121. November 1865 – June 1866. Retrieved 12 November 2009. 
  42. ^ Broome, D.C. (1963). "The development of the modern asphalt road". The Surveyor and municipal and county engineer. London. 122 (3278 & 3279): 1437–1440 & 1472–1475Snippet view: Simms & Claridge p.1439 
  43. ^ Phipson, Dr T. Lamb (1902). Confessions of a Violinist: Realities and Romance. London: Chatto & Windus. p. 11. Retrieved 26 November 2009.  Full text at Internet Archive (archive.org)
  44. ^ "Claridge's UK Patents in 1837 & 1838". The London Gazette. 25 February 1851. p. 489. 
  45. ^ a b Hobhouse, Hermione (General Editor) (1994). "British History Online". 'Northern Millwall: Tooke Town', Survey of London: volumes 43 and 44: Poplar, Blackwall and Isle of Dogs. pp. 423–433 (see text at refs 169 & 170). Retrieved 8 November 2009. 
  46. ^ "Claridge's Scottish and Irish Patents in 1838". The Mechanic's magazine, museum, register, journal and gazette. 29. London: W.A. Robertson. 7 April – 29 September 1838. pp. vii, viii, 64, 128. 
  47. ^ a b "Joint Stock Companies (description of asphalte use by Claridge's company)". The Civil Engineer and Architects Journal. Vol. 1. London. October 1837 – December 1838. p. 199. Retrieved 16 November 2009.  Full text at Internet Archive (archive.org). Alternative viewing at: https://books.google.com/books?id=sQ5AAAAAYAAJ&pg
  48. ^ Miles, Lewis (2000), pp.10.06.1–2
  49. ^ a b Comments on asphalt patents of R.T. Claridge, Esq (1904), p.18
  50. ^ a b Miles, Lewis (2000), p.10.06.2
  51. ^ "1838 bitumen UK uses by Robinson's and Claridge's companies, & the Bastenne company". The Mechanic's magazine, museum, register, journal and gazette. 29. London: W.A. Robertson. 22 September 1838. p. 448. 
  52. ^ Gerhard, W.M. Paul (1908). Modern Baths and Bath Houses (1st ed.). New York: John Wiley and Sons.  (Enter "asphalt" into the search field for list of pages discussing the subject)
  53. ^ "Claridge's Patent Asphalte Co. ventures into tarred slag macadam", Concrete and Constructional Engineering, London, IX (1): 760, January 1914, retrieved 15 June 2010 
  54. ^ "Registration of Clarmac Roads", The Law Reports: Chancery Division, Vol. 1: 544–547, 1921, retrieved 17 June 2010 
  55. ^ "Clarmac and Clarphalte", The Building News and Engineering Journal, Vol. 109: July to December 1915 (No. 3157): 2–4 (n13–15 in electronic page field), 7 July 1915, retrieved 18 June 2010 
  56. ^ Roads laid with Clarmac The Building News and Engineering Journal, 1915 109 (3157), p.3 (n14 in electronic field).
  57. ^ a b Clarmac financial difficults due to WW1 Debentures deposited The Law Reports: Chancery Division, (1921) Vol. 1 p.545. Retrieved 17 June 2010.
  58. ^ "Notice of the Winding up of Clarmac Roads", The London Gazette (29340): 10568, 26 October 1915, retrieved 15 June 2010 
  59. ^ a b Claridge's Patent Asphalte Co. compulsorily wound up Funds invested in new company The Law Times Reports (1921) Vol.125, p.256. Retrieved 15 June 2010.
  60. ^ "Claridge's Patent Asphalte Co. winds up 10 November 1917". The London Gazette. 16 November 1917. p. 11863. 
  61. ^ Hobhouse, Hermione (General Editor) (1994). "British History Online". 'Cubitt Town: Riverside area: from Newcastle Drawdock to Cubitt Town Pier', Survey of London: volumes 43 and 44: Poplar, Blackwall and Isle of Dogs. pp. 528–532 (see text at refs 507 & 510). Retrieved 8 November 2009. 
  62. ^ Stockton, Nick (23 June 2017). "Plastic Water Bottles Might Have Poisoned Ancient Californians". Wired. Retrieved 26 June 2017. 
  63. ^ McNichol, Dan (2005). Paving the Way: Asphalt in America. Lanham, MD: National Asphalt Pavement Association. ISBN 0-914313-04-5. Archived from the original on 2006-08-29. 
  64. ^ David O. Whitten, "A Century of Parquet Pavements: Wood as a Paving Material In The United States And Abroad, 1840-1940." Essays in Economic and Business History 15 (1997): 209-26.
  65. ^ Arthur Maier Schlesinger, The Rise of the City: 1878-1898 (1933) p 88-93.
  66. ^ John D. Fairfield, "Rapid Transit: Automobility and Settlement in Urban America" Reviews in American History 23#1 (1995), pp. 80-85 online.
  67. ^ "Robert C. Fitzsimmons (1881–1971)". Canadian Petroleum Hall of Fame. 2010. Retrieved 2016-01-20. 
  68. ^ "Bitumount". Government of Alberta. 2016. Retrieved 2016-01-20. 
  69. ^ Niépce Museum history pages. Retrieved 27 October 2012. Archived 3 August 2007 at the Wayback Machine.
  70. ^ The First Photograph (Harry Ransom Center, University of Texas at Austin). Retrieved 27 October 2012.
  71. ^ Spiegelman, Willard (2009-08-21). "Revolutionary Romanticism: 'The Raft of the Medusa' brought energy to French art". The Wall Street Journal. New York City. Retrieved 2016-01-27. 
  72. ^ The Asphalt Paving Industry: A Global Perspective, 2nd Edition (PDF). Lanham, Maryland, and Brussels: National Asphalt Pavement Association and European Asphalt Pavement Association. February 2011. ISBN 0-914313-06-1. Retrieved 27 September 2012. 
  73. ^ "How Should We Express RAP and RAS Contents?". Asphalt Technology E-News. 26 (2). 2014. Archived from the original on 9 June 2015. Retrieved 2015-08-13. 
  74. ^ "Highway Statistics Series: Public Road Length Miles by Type of Surface and Ownership". Federal Highway Administration. 2013-10-01. Retrieved 2015-08-13. 
  75. ^ "Asphalt Pavement Recycling". Annual Asphalt Pavement Industry Survey on Recycled Materials and Warm-Mix Asphalt Usage: 2009–2013. National Asphalt Pavement Association. Retrieved 13 August 2015. 
  76. ^ a b "Crude Oil and Petroleum Products". National Energy Board of Canada. Retrieved January 21, 2016. 
  77. ^ a b c "2015 CAPP Crude Oil Forecast, Markets & Transportation". Canadian Association of Petroleum Producers. Archived from the original on 20 January 2016. Retrieved January 21, 2016. 
  78. ^ "The Project". North West Redwater Partnership. Retrieved January 21, 2016. 
  79. ^ Rodier, J., Scheidhauer, J., & Malabre, M. (1961). The conditioning of radioactive waste by bitumen (No. CEA-R—1992). CEA Marcoule.
  80. ^ Lefillatre, G., Rodier, J., Hullo, R., Cudel, Y., & Rodi, L. (1969). Use of a thin-film evaporator for bitumen coating of radioactive concentrates (No. CEA-R—3742). CEA Marcoule.
  81. ^ Sato, Y., Miura, A., Kato, Y., Suzuki, H., Shigetome, Y., Koyama, T., ... & Yamanouchi, T. (2000). Study on the cause of the fire and explosion incident at Bituminization Demonstration Facility of PNC Tokai Works. In Nuclear waste: from research to industrial maturity. International conference (pp. 179–190).
  82. ^ Okada, K., Nur, R. M., & Fujii, Y. (1999). The formation of explosive compounds in bitumen/nitrate mixtures. Journal of hazardous materials, 69(3), 245–256.
  83. ^ Johnson, D.I., Hitchon, J.W., & Phillips, D.C. (1986). Further observations of the swelling of bitumens and simulated bitumen wasteforms during γ-irradiation (No. AERE-R—12292). UKAEA Harwell Lab. Materials Development Division.
  84. ^ Phillips, D. C., Hitchon, J. W., Johnson, D. I., & Matthews, J. R. (1984). The radiation swelling of bitumens and bitumenised wastes. Journal of nuclear materials, 125(2), 202–218.
  85. ^ Ait-Langomazino, N., Sellier, R., Jouquet, G., & Trescinski, M. (1991). Microbial degradation of bitumen. Experientia, 47(6), 533–539.
  86. ^ Mohd, Meraj Jafri; Singh, D. K. (march 2013). "Cashew Nutshell Liquid Resin" (PDF). IJRREST: International Journal of Research Review in Engineering Science and Technology. 2: 60–65.  Check date values in: |date= (help)
  87. ^ Hesp, Simon A.M.; Herbert F. Shurvell (2010). "X-ray fluorescence detection of waste engine oil residue in asphalt and its effect on cracking in service". International Journal of Pavement Engineering. 11 (6): 541–553. doi:10.1080/10298436.2010.488729. ISSN 1029-8436. Retrieved 2014-03-24. 
  88. ^ Heat Island Effect. From the website of the US Environmental Protection Agency.
  89. ^ Giavarini, Carlo (March 2013). Six Thousand Years of Asphalt. SITEB. pp. 71–78. ISBN 978-88-908408-3-8. 
  90. ^ [3], Selenice Bitumi for more information about Selenizza
  91. ^ Giavarini, C.; Pellegrini, A. "Life cycle assessment of Selenice asphalt compared with petroleum bitumen". The 1st Albanian Congress on Roads: 234–237. 
  92. ^ "CDC – NIOSH Pocket Guide to Chemical Hazards – Asphalt fumes". www.cdc.gov. Retrieved 2015-11-27. 
  93. ^ IARC (2013). Bitumens and Bitumen Emissions, and Some N- and S-Heterocyclic Polycyclic Aromatic Hydrocarbons. 103. Lyon, France: International Agency for Research on Cancer. ISBN 978-92-832-1326-0. Retrieved 2015-12-07. 
  94. ^ Cavallari, J. M.; Zwack, L. M.; Lange, C. R.; Herrick, R. F.; Mcclean, M. D. (2012). "Temperature-Dependent Emission Concentrations of Polycyclic Aromatic Hydrocarbons in Paving and Built-Up Roofing Asphalts". Annals of Occupational Hygiene. 56 (2): 148–160. doi:10.1093/annhyg/mer107 . ISSN 0003-4878. 
  95. ^ "Contacto – Eco Roofing". epdmecoroofing.com. 
  96. ^ "Follow the evolution of the road from path to pavement". 


Road surface

Asphalt Driveway Price Raised sidewalks beside a 2000-year-old paved road, Pompeii, Italy

A sidewalk (American English) or pavement (British English), also known as a footpath or footway, is a path along the side of a road. A sidewalk may accommodate moderate changes in grade (height) and is normally separated from the vehicular section by a curb. There may also be a median strip or road verge (a strip of vegetation, grass or bushes or trees or a combination of these) either between the sidewalk and the roadway or between the sidewalk and the boundary.

In some places, the same term may also be used for a paved path, trail or footpath that is not next to a road, for example, a path through a park.

The term "sidewalk" is usually preferred in most of North America, along with many other countries worldwide that are not members of the Commonwealth of Nations. The term "pavement" is more common in the United Kingdom,[1] as well as parts of the Mid-Atlantic United States such as Philadelphia and New Jersey.[2][3] Many Commonwealth countries use the term "footpath". The professional, civil engineering and legal term for this in North America is "sidewalk" while in the United Kingdom it is "footway".[4]

In the United States, the term sidewalk is used for the pedestrian path beside a road. "Shared use paths" or "multi-use paths" are available for use by both pedestrians and bicyclists.[5] "Walkway" is a more comprehensive term that includes stairs, ramps, passageways, and related structures that facilitate the use of a path as well as the sidewalk.[6]

In the UK, the term "footpath" is mostly used for paths that do not abut a roadway.[7] The term "shared-use path" is used where cyclists are also able to use the same section of path as pedestrians.[8]

East India House, Leadenhall Street, London, 1766. The sidewalk is separated from the main street by six bollards in front of the building.

There is evidence that sidewalks were built in ancient times. It was claimed that the Greek city of Corinth was paved by the 4th-century, and the Romans were particularly prolific sidewalk builders – they called them semitas.[9]

However, by the Middle Ages, narrow roads had reverted to being simultaneously used by pedestrians and wagons without any formal separation between the two categories. Early attempts at ensuring the adequate maintenance of foot-ways or sidewalks were often made, such as the 1623 Act for Colchester, although they were generally not very effective.[10]

Following the Great Fire of London in 1666, attempts were slowly made to bring some order to the sprawling city. In 1671, 'Certain Orders, Rules and Directions Touching the Paving and Cleansing The Streets, Lanes and Common Passages within the City of London' were formulated, calling for all streets to be adequately paved for pedestrians with cobblestones. Purbeck stone was widely used as a durable paving material. Bollards were also installed to protect pedestrians from the traffic in the middle of the road.

A series of Paving Acts from the House of Commons during the 18th century, especially the 1766 Paving & Lighting Act, authorized the City of London Corporation to create foot-ways throughout all the streets of London, to pave them with Purbeck stone (the thoroughfare in the middle was generally cobblestone) and to raise them above the street level with curbs forming the separation.[11] The Corporation was also made responsible for the regular upkeep of the roads, including their cleaning and repair, for which they charged a tax from 1766.[12] By the late 19th-century large and spacious sidewalks were routinely constructed in European capitals, and were associated with urban sophistication.

In the United States, adjoining property owners must in most situations finance all or part of the cost of sidewalk construction. In a legal case in 1917 involving E. L. Stewart, a former member of the Louisiana House of Representatives and a lawyer in Minden in Webster Parish, the Louisiana Supreme Court ruled that owners must pay whether they wish for the sidewalk to be constructed or not.[13]

Pedestrians walking on the pavement (sidewalk) in London.

Sidewalks play an important role in transportation, as they provide a safe path for people to walk along that is separated from the motorized traffic. They aid road safety by minimizing interaction between pedestrians and motorized traffic. Sidewalks are normally in pairs, one on each side of the road, with the center section of the road for motorized vehicles.

In rural roads, sidewalks may not be present as the amount of traffic (pedestrian or motorized) may not be enough to justify separating the two. In suburban and urban areas, sidewalks are more common. In town and city centers (known as downtown in North America) the amount of pedestrian traffic can exceed motorized traffic, and in this case the sidewalks can occupy more than half of the width of the road, or the whole road can be reserved for pedestrians, see Pedestrian zone.

Sidewalks may have a small effect on reducing vehicle miles traveled and carbon dioxide emissions. A study of sidewalk and transit investments in Seattle neighborhoods found vehicle travel reductions of 6 to 8% and CO2 emission reductions of 1.3 to 2.2% [14]

Sidewalk with bike path See also: Road traffic safety

Research commissioned for the Florida Department of Transportation, published in 2005, found that, in Florida, the Crash Reduction Factor (used to estimate the expected reduction of crashes during a given period) resulting from the installation of sidewalks averaged 74%.[15] Research at the University of North Carolina for the U.S. Department of Transportation found that the presence or absence of a sidewalk and the speed limit are significant factors in the likelihood of a vehicle/pedestrian crash. Sidewalk presence had a risk ratio of 0.118, which means that the likelihood of a crash on a road with a paved sidewalk was 88.2 percent lower than one without a sidewalk. “This should not be interpreted to mean that installing sidewalks would necessarily reduce the likelihood of pedestrian/motor vehicle crashes by 88.2 percent in all situations. However, the presence of a sidewalk clearly has a strong beneficial effect of reducing the risk of a ‘walking along roadway’ pedestrian/motor vehicle crash.” The study does not count crashes that happen when walking across a roadway. The speed limit risk ratio was 1.116, which means that a 16.1-km/h (10-mi/h) increase in the limit yields a factor of (1.116)10 or 3.[16]

The presence or absence of sidewalks was one of three factors that were found to encourage drivers to choose lower, safer speeds.[17]

On the other hand, the implementation of schemes which involve the removal of sidewalks, such as shared space schemes, are reported to deliver a dramatic drop in crashes and congestion too, which indicates that a number of other factors, such as the local speed environment, also play an important role in whether sidewalks are necessarily the best local solution for pedestrian safety.[18]

In cold weather, black ice is a common problem with unsalted sidewalks. The ice forms a thin transparent surface film which is almost impossible to see, and so results in many slips by pedestrians.

Riding bicycles on sidewalks is discouraged since some research shows it to be more dangerous than riding in the street.[19] Some jurisdictions prohibit sidewalk riding except for children. In addition to the risk of cyclist/pedestrian collisions, cyclists face increase risks from collisions with motor vehicles at street crossings and driveways. Riding in the direction opposite to traffic in the adjacent lane is especially risky.[20]

Since residents of neighborhoods with sidewalks are more likely to walk, they tend to have lower rates of cardiovascular disease, obesity, and other health issues related to sedentary lifestyles.[21] Also, children who walk to school have been shown to have better concentration.[22]

Native Americans busking at Orchard Road, Singapore

Some sidewalks may be used as social spaces with sidewalk cafes, markets, or busking musicians, as well as for parking for a variety of vehicles including cars, motorbikes and bicycles.

Contemporary sidewalks are most often made of concrete in the United States and Canada, while tarmac, asphalt, brick, stone, slab and (increasingly) rubber are more common in Europe.[23] Different materials are more or less friendly environmentally: pumice-based trass, for example, when used as an extender is less energy-intensive than Portland cement concrete or petroleum-based materials such as asphalt or tar-penetration macadam). Multi-use paths alongside roads are sometimes made of materials that are softer than concrete, such as asphalt.

In the 19th century and early 20th century, sidewalks of wood were common in some North American locations. They may still be found at historic beach locations and in conservation areas to protect the land beneath and around, called boardwalks.

Brick sidewalks are found in some urban areas, usually for aesthetic purposes. Brick sidewalk construction usually involves the usage of a mechanical vibrator to lock the bricks in place after they have been laid (and/or to prepare the soil before laying). Although this might also be done by other tools (as regular hammers and heavy rolls), a vibrator is often used to speed up the process.

Stone slabs called flagstones or flags are sometimes used where an attractive appearance is required, as in historic town centers. In other places, pre-cast concrete slabs (called paving slabs or, less correctly, paving stones) are used. These may be colored or textured to resemble stone.

Freshly laid concrete sidewalk, with horizontal strain-relief grooves faintly visible

In the United States and Canada, the most common type of sidewalk consists of a poured concrete ribbon, examples of which from as early as the 1860s can be found in good repair in San Francisco, and stamped with the name of the contractor and date of installation.[citation needed] When quantities of Portland cement were first imported to the United States in the 1880s, its principal use was in the construction of sidewalks.[24]

Today, most sidewalk ribbons are constructed with cross-lying strain-relief grooves placed or sawn at regular intervals typically 5 feet (1.5 m) apart. This partitioning, an improvement over the continuous slab, was patented in 1924 by Arthur Wesley Hall and William Alexander McVay, who wished to minimize damage to the concrete from the effects of tectonic and temperature fluctuations, both of which can crack longer segments.[25] The technique is not perfect, as freeze-thaw cycles (in cold-weather regions) and tree root growth can eventually result in damage which requires repair.

In highly variable climates which undergo multiple freeze-thaw cycles, the concrete blocks will be separated by expansion joints to allow for thermal expansion without breakage. The use of expansion joints in sidewalks may not be necessary, as the concrete will shrink while setting.[26]

In the United Kingdom, Australia and France suburban sidewalks are most commonly constructed of tarmac. In urban or inner-city areas sidewalks are most commonly constructed of slabs, stone, or brick depending upon the surrounding street architecture and furniture.

Paver Repair Quotes

https://www.helpwikileaks.co.za/kempton-park/

Help Wiki Leaks Have Asphalt Paving Contractors List

Asphalt Paving Contractors Kempton park

How Do You Select The Best Driveway or Asphalt Paving Contractors?

Driveway to a farm Driveway apron and sloped curb to a public street, all under construction

A driveway (also called drive in UK English) Asphalt Paving Contractors  in Gauteng is a type of private road for local access to one or a small group of structures, and is owned and maintained by an individual or group.

Asphalt Construction Quotes

Driveways rarely have traffic lights, but some that bear heavy traffic, especially those leading to commercial businesses and parks, do.

Driveways may be decorative in ways that public roads cannot, because of their lighter traffic and the willingness of owners to invest in their construction. Driveways are not resurfaced, snow blown or otherwise maintained by governments. They are generally designed to conform to the architecture of connected houses or other buildings.

Driveway Paving Contractors Near Me

Some of the materials that can be used for driveways include concrete, decorative brick, cobblestone, block paving, asphalt, gravel, decomposed granite, and surrounded with grass or other ground-cover plants.

Alley

Residential Paving Cost Estimate

Driveways are commonly used as paths to private garages, carports, or houses. On large estates, a driveway may be the road that leads to the house from the public road, possibly with a gate in between. Some driveways divide to serve different homeowners. A driveway may also refer to a small apron of pavement in front of a garage with a curb cut in the sidewalk, sometimes too short to accommodate a car.

Residential Paving Cost Estimate

Often, either by choice or to conform with local regulations, cars are parked in driveways in order to leave streets clear for traffic. Moreover, some jurisdictions prohibit parking or leaving standing any motor vehicle upon any residential lawn area (defined as the property from the front of a residential house, condominium, or cooperative to the street line other than a driveway, walkway, concrete or blacktopped surface parking space).[2] Other examples include the city of Berkeley, California that forbids “any person to park or leave standing, or cause to be parked or left standing any vehicle upon any public street in the City for seventy-two or more consecutive hours.”[3] Other areas may prohibit leaving vehicles on residential streets during certain times (for instance, to accommodate regular street cleaning), necessitating the use of driveways.

Toll road

Tarmac Driveways Near Me

Residential driveways are also used for such things as garage sales, automobile washing and repair, and recreation, notably (in North America) for basketball practice.

Another form of driveway is a ‘Run-Up’, or short piece of land used usually at the front of the property to park a vehicle on.[citation needed]

Interesting Facts About Asphalt Paving Contractors in Parkmore:

About Asphalt Paving Contractors in Parkmore:

Paver Repair Quotes Sealcoating a road on the University of California, Davis campus in 2013.

Sealcoating, or pavement sealing, is the process of applying a protective coating to asphalt-based pavements to provide a layer of protection from the elements: water, oils, and U.V. damage.

Sealcoat or pavement sealer is a coating for asphalt-based pavements. Sealcoating is marketed as a protective coating that extends the life of asphalt pavements. There is not any independent research that proves these claims.

Sealcoating may also reduce the friction or anti-skid properties associated with the exposed aggregates in asphalt.

Not all pavement sealcoat are created equal. For example, refined tar-based sealer offers the best protecting against water penetration and chemical resistance. Asphalt-based sealer typically offers poor protection against environmental chemical and harsher climates (salt water). Petroleum-based sealer offer protection against water and chemicals somewhere between the other two sealers. Another difference between coatings is in terms of wear. Again, refined tar-based sealer offers the best wear characteristics (typically 3–5 years) while asphalt-based sealer may last 1–3 years. Petroleum-based sealer falls between refined tar and asphalt.

There are concerns about pavement sealer polluting the environment after it is abraded from the surface of the pavement. Some states in North America have banned the use of coal tar–based sealants primarily based on United States Geological Survey studies.[1] The industry group that represents sealcoat manufacturers has performed numerous research and reviews of the USGS and have found it to be erroneous, biased (citation and white hat, to name a few) and too generalized in order to draw the conclusions that the United States Geological Survey claims.

There are primarily three types of pavement sealers. They are commonly known as refined tar-based (coal tar based), asphalt-based, and petroleum-based. All three have their advantages but are typically chosen by the contractors’ preference unless otherwise specified.

Prior to application the surface must be completely clean and dry using sweeping methods and/or blowers. If the surface is not clean and dry, then poor adhesion will result. Pavement sealers are applied with either pressurized spray equipment, or self-propelled squeegee machines or by hand with a squeegee. Equipment must have continuous agitation to maintain consistency of the sealcoat mix. The process is typically a two-coat application which requires 24 to 48 hours of curing before vehicles can be allowed back on the surface. Once the surface is properly prepared, then properly mixed sealer will be applied at about 60 square feet per gallon per coat.

The Sealcoating Process

Some studies that suggest that refined tar sealants are a significant contributor to polycyclic aromatic hydrocarbon levels in streams and creek beds and that the continual application of sealcoats may be a significant factor. As a result, a few municipalities in the United States have banned this material.[2] The same studies also suggest that it can be harmful if ingested before curing and ingesting soil or dust contaminated by eroded coal tar sealant.[3] It is also known to have effects on fish and other animals that live in water.

Asphalt Paving Contractors in Parkmore

The Paving Company Near Me For other uses, see Asphalt (disambiguation). Note: The terms bitumen and asphalt are mostly interchangeable, except where asphalt is used as a shorthand for asphalt concrete. Natural bitumen from the Dead Sea Refined asphalt The University of Queensland pitch drop experiment, demonstrating the viscosity of asphalt

Asphalt (/ˈæsˌfɔːlt, -ˌfɑːlt/), also known as bitumen (UK English: /ˈbɪəmən, ˈbɪtjʊmən/,[1] US English: /bɪˈt(j)mən, bˈt(j)mən/)[2] is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used.[3] The word is derived from the Ancient Greek ἄσφαλτος ásphaltos.[4]

The primary use (70%) of asphalt is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs.[5]

The terms "asphalt" and "bitumen" are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, "asphalt" (or "asphalt cement") is commonly used for a refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called "bitumen", and geologists worldwide often prefer the term for the naturally occurring variety. Common colloquial usage often refers to various forms of asphalt as "tar", as in the name of the La Brea Tar Pits.

Naturally occurring asphalt is sometimes specified by the term "crude bitumen". Its viscosity is similar to that of cold molasses[6][7] while the material obtained from the fractional distillation of crude oil boiling at 525 °C (977 °F) is sometimes referred to as "refined bitumen". The Canadian province of Alberta has most of the world's reserves of natural asphalt in the Athabasca oil sands, which cover 142,000 square kilometres (55,000 sq mi), an area larger than England.[8]

The word "asphalt" is derived from the late Middle English, in turn from French asphalte, based on Late Latin asphalton, asphaltum, which is the latinisation of the Greek ἄσφαλτος (ásphaltos, ásphalton), a word meaning "asphalt/bitumen/pitch",[9] which perhaps derives from ἀ-, "without" and σφάλλω (sfallō), "make fall".[10] The first use of asphalt by the ancients was in the nature of a cement for securing or joining together various objects, and it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall.[11] From the Greek, the word passed into late Latin, and thence into French (asphalte) and English ("asphaltum" and "asphalt"). In French, the term asphalte is used for naturally occurring asphalt-soaked limestone deposits, and for specialised manufactured products with fewer voids or greater bitumen content than the "asphaltic concrete" used to pave roads.

The expression "bitumen" originated in the Sanskrit words jatu, meaning "pitch", and jatu-krit, meaning "pitch creating" or "pitch producing" (referring to coniferous or resinous trees). The Latin equivalent is claimed by some to be originally gwitu-men (pertaining to pitch), and by others, pixtumens (exuding or bubbling pitch), which was subsequently shortened to bitumen, thence passing via French into English. From the same root is derived the Anglo-Saxon word cwidu (mastix), the German word Kitt (cement or mastic) and the old Norse word kvada.[12]

In British English, "bitumen" is used instead of "asphalt". The word "asphalt" is instead used to refer to asphalt concrete, a mixture of construction aggregate and asphalt itself (also called "tarmac" in common parlance). Bitumen mixed with clay was usually called "asphaltum",[13] but the term is less commonly used today.[citation needed]

In Australian English, "bitumen" is often used as the generic term for road surfaces.

In American English, "asphalt" is equivalent to the British "bitumen". However, "asphalt" is also commonly used as a shortened form of "asphalt concrete" (therefore equivalent to the British "asphalt" or "tarmac").

In Canadian English, the word "bitumen" is used to refer to the vast Canadian deposits of extremely heavy crude oil,[14] while "asphalt" is used for the oil refinery product. Diluted bitumen (diluted with naphtha to make it flow in pipelines) is known as "dilbit" in the Canadian petroleum industry, while bitumen "upgraded" to synthetic crude oil is known as "syncrude", and syncrude blended with bitumen is called "synbit".[15]

"Bitumen" is still the preferred geological term for naturally occurring deposits of the solid or semi-solid form of petroleum. "Bituminous rock" is a form of sandstone impregnated with bitumen. The tar sands of Alberta, Canada are a similar material.

Neither of the terms "asphalt" or "bitumen" should be confused with tar or coal tars.[further explanation needed]

See also: Asphaltene

The components of asphalt include four main classes of compounds:

The naphthene aromatics and polar aromatics are typically the majority components. Most natural bitumens also contain organosulfur compounds, resulting in an overall sulfur content of up to 4%. Nickel and vanadium are found at <10 parts per million, as is typical of some petroleum.[5]

The substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase.[16] "It is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large".[17]

Asphalt may be confused with coal tar, which is a visually similar black, thermoplastic material produced by the destructive distillation of coal. During the early and mid-20th century, when town gas was produced, coal tar was a readily available byproduct and extensively used as the binder for road aggregates. The addition of coal tar to macadam roads led to the word "tarmac", which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, asphalt has completely overtaken the use of coal tar in these applications. Other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. "Pitch" is another term sometimes informally used at times to refer to asphalt, as in Pitch Lake.

Bituminous outcrop of the Puy de la Poix, Clermont-Ferrand, France

The majority of asphalt used commercially is obtained from petroleum.[18] Nonetheless, large amounts of asphalt occur in concentrated form in nature. Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae (diatoms) and other once-living things. These remains were deposited in the mud on the bottom of the ocean or lake where the organisms lived. Under the heat (above 50 °C) and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.

Natural deposits of bitumen include lakes such as the Pitch Lake in Trinidad and Tobago and Lake Bermudez in Venezuela. Natural seeps occur in the La Brea Tar Pits and in the Dead Sea.

Bitumen also occurs in unconsolidated sandstones known as "oil sands" in Alberta, Canada, and the similar "tar sands" in Utah, US. The Canadian province of Alberta has most of the world's reserves, in three huge deposits covering 142,000 square kilometres (55,000 sq mi), an area larger than England or New York state. These bituminous sands contain 166 billion barrels (26.4×10^9 m3) of commercially established oil reserves, giving Canada the third largest oil reserves in the world. Although historically it was used without refining to pave roads, nearly all of the output is now used as raw material for oil refineries in Canada and the United States.[8]

The world's largest deposit of natural bitumen, known as the Athabasca oil sands, is located in the McMurray Formation of Northern Alberta. This formation is from the early Cretaceous, and is composed of numerous lenses of oil-bearing sand with up to 20% oil.[19] Isotopic studies show the oil deposits to be about 110 million years old.[20] Two smaller but still very large formations occur in the Peace River oil sands and the Cold Lake oil sands, to the west and southeast of the Athabasca oil sands, respectively. Of the Alberta deposits, only parts of the Athabasca oil sands are shallow enough to be suitable for surface mining. The other 80% has to be produced by oil wells using enhanced oil recovery techniques like steam-assisted gravity drainage.[21]

Much smaller heavy oil or bitumen deposits also occur in the Uinta Basin in Utah, US. The Tar Sand Triangle deposit, for example, is roughly 6% bitumen.[19]

Bitumen may occur in hydrothermal veins. An example of this is within the Uinta Basin of Utah, in the US, where there is a swarm of laterally and vertically extensive veins composed of a solid hydrocarbon termed Gilsonite. These veins formed by the polymerization and solidification of hydrocarbons that were mobilized from the deeper oil shales of the Green River Formation during burial and diagenesis.[22]

Bitumen is similar to the organic matter in carbonaceous meteorites.[23] However, detailed studies have shown these materials to be distinct.[24] The vast Alberta bitumen resources are considered to have started out as living material from marine plants and animals, mainly algae, that died millions of years ago when an ancient ocean covered Alberta. They were covered by mud, buried deeply over time, and gently cooked into oil by geothermal heat at a temperature of 50 to 150 °C (120 to 300 °F). Due to pressure from the rising of the Rocky Mountains in southwestern Alberta, 80 to 55 million years ago, the oil was driven northeast hundreds of kilometres and trapped into underground sand deposits left behind by ancient river beds and ocean beaches, thus forming the oil sands.[21]

The use of natural bitumen for waterproofing, and as an adhesive dates at least to the fifth millennium BC, with a crop storage basket discovered in Mehrgarh, of the Indus Valley Civilization, lined with it.[25] By the 3rd millennia BC refined rock asphalt was in use, in the region, and was used to waterproof the Great Bath, Mohenjo-daro.

In the ancient Middle East, the Sumerians used natural bitumen deposits for mortar between bricks and stones, to cement parts of carvings, such as eyes, into place, for ship caulking, and for waterproofing.[3] The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon.[26]

The 1 kilometre (0.62 mi) long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis (ca. 800 BC) was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent.[27]

Bitumen was used by ancient Egyptians to embalm mummies.[3][28] The Persian word for asphalt is moom, which is related to the English word mummy. The Egyptians' primary source of bitumen was the Dead Sea, which the Romans knew as Palus Asphaltites (Asphalt Lake).

Approximately 40 AD, Dioscorides described the Dead Sea material as Judaicum bitumen, and noted other places in the region where it could be found.[29] The Sidon bitumen is thought to refer to material found at Hasbeya.[30] Pliny refers also to bitumen being found in Epirus. It was a valuable strategic resource, the object of the first known battle for a hydrocarbon deposit—between the Seleucids and the Nabateans in 312 BC.[31]

In the ancient Far East, natural bitumen was slowly boiled to get rid of the higher fractions, leaving a thermoplastic material of higher molecular weight that when layered on objects became quite hard upon cooling. This was used to cover objects that needed waterproofing,[3] such as scabbards and other items. Statuettes of household deities were also cast with this type of material in Japan, and probably also in China.

In North America, archaeological recovery has indicated bitumen was sometimes used to adhere stone projectile points to wooden shafts.[32] In Canada, aboriginal people used bitumen seeping out of the banks of the Athabasca and other rivers to waterproof birch bark canoes, and also heated it in smudge pots to ward off mosquitoes in the summer.[21]

In 1553, Pierre Belon described in his work Observations that pissasphalto, a mixture of pitch and bitumen, was used in the Republic of Ragusa (now Dubrovnik, Croatia) for tarring of ships.[33]

An 1838 edition of Mechanics Magazine cites an early use of asphalt in France. A pamphlet dated 1621, by "a certain Monsieur d'Eyrinys, states that he had discovered the existence (of asphaltum) in large quantities in the vicinity of Neufchatel", and that he proposed to use it in a variety of ways – "principally in the construction of air-proof granaries, and in protecting, by means of the arches, the water-courses in the city of Paris from the intrusion of dirt and filth", which at that time made the water unusable. "He expatiates also on the excellence of this material for forming level and durable terraces" in palaces, "the notion of forming such terraces in the streets not one likely to cross the brain of a Parisian of that generation".[34]

But the substance was generally neglected in France until the revolution of 1830. In the 1830s there was a surge of interest, and asphalt became widely used "for pavements, flat roofs, and the lining of cisterns, and in England, some use of it had been made of it for similar purposes". Its rise in Europe was "a sudden phenomenon", after natural deposits were found "in France at Osbann (Bas-Rhin), the Parc (Ain) and the Puy-de-la-Poix (Puy-de-Dôme)", although it could also be made artificially.[35] One of the earliest uses in France was the laying of about 24,000 square yards of Seyssel asphalt at the Place de la Concorde in 1835.[36]

Among the earlier uses of bitumen in the United Kingdom was for etching. William Salmon's Polygraphice (1673) provides a recipe for varnish used in etching, consisting of three ounces of virgin wax, two ounces of mastic, and one ounce of asphaltum.[37] By the fifth edition in 1685, he had included more asphaltum recipes from other sources.[38]

The first British patent for the use of asphalt was "Cassell's patent asphalte or bitumen" in 1834.[35] Then on 25 November 1837, Richard Tappin Claridge patented the use of Seyssel asphalt (patent #7849), for use in asphalte pavement,[39][40] having seen it employed in France and Belgium when visiting with Frederick Walter Simms, who worked with him on the introduction of asphalt to Britain.[41][42] Dr T. Lamb Phipson writes that his father, Samuel Ryland Phipson, a friend of Claridge, was also "instrumental in introducing the asphalte pavement (in 1836)".[43] Indeed, mastic pavements had been previously employed at Vauxhall by a competitor of Claridge, but without success.[36]

Claridge obtained a patent in Scotland on 27 March 1838, and obtained a patent in Ireland on 23 April 1838. In 1851, extensions for the 1837 patent and for both 1838 patents were sought by the trustees of a company previously formed by Claridge.[35][44][45][46] Claridge's Patent Asphalte Company—formed in 1838 for the purpose of introducing to Britain "Asphalte in its natural state from the mine at Pyrimont Seysell in France",[47]—"laid one of the first asphalt pavements in Whitehall".[48] Trials were made of the pavement in 1838 on the footway in Whitehall, the stable at Knightsbridge Barracks,[47][49] "and subsequently on the space at the bottom of the steps leading from Waterloo Place to St. James Park".[49] "The formation in 1838 of Claridge's Patent Asphalte Company (with a distinguished list of aristocratic patrons, and Marc and Isambard Brunel as, respectively, a trustee and consulting engineer), gave an enormous impetus to the development of a British asphalt industry".[45] "By the end of 1838, at least two other companies, Robinson's and the Bastenne company, were in production",[50] with asphalt being laid as paving at Brighton, Herne Bay, Canterbury, Kensington, the Strand, and a large floor area in Bunhill-row, while meantime Claridge's Whitehall paving "continue(d) in good order".[51]

In 1838, there was a flurry of entrepreneurial activity involving asphalt, which had uses beyond paving. For example, asphalt could also be used for flooring, damp proofing in buildings, and for waterproofing of various types of pools and baths, both of which were also proliferating in the 19th century.[3][35][52] On the London stockmarket, there were various claims as to the exclusivity of asphalt quality from France, Germany and England. And numerous patents were granted in France, with similar numbers of patent applications being denied in England due to their similarity to each other. In England, "Claridge's was the type most used in the 1840s and 50s".[50]

In 1914, Claridge's Company entered into a joint venture to produce tar-bound macadam,[53] with materials manufactured through a subsidiary company called Clarmac Roads Ltd.[54] Two products resulted, namely Clarmac, and Clarphalte, with the former being manufactured by Clarmac Roads and the latter by Claridge's Patent Asphalte Co., although Clarmac was more widely used.[55][note 1] However, the First World War ruined the Clarmac Company, which entered into liquidation in 1915.[57][58] The failure of Clarmac Roads Ltd had a flow-on effect to Claridge's Company, which was itself compulsorily wound up,[59] ceasing operations in 1917,[60][61] having invested a substantial amount of funds into the new venture, both at the outset[59] and in a subsequent attempt to save the Clarmac Company.[57]

The first use of bitumen in the New World was by indigenous peoples. On the west coast, as early as the 13th century, the Tongva, Luiseño and Chumash peoples collected the naturally occurring bitumen that seeped to the surface above underlying petroleum deposits. All three groups used the substance as an adhesive. It is found on many different artifacts of tools and ceremonial items. For example, it was used on rattles to adhere gourds or turtle shells to rattle handles. It was also used in decorations. Small round shell beads were often set in asphaltum to provide decorations. It was used as a sealant on baskets to make them watertight for carrying water, possibly poisoning those who drank the water.[62] Asphalt was used also to seal the planks on ocean-going canoes.

Asphalt was first used to pave streets in the 1870s. At first naturally occurring "bituminous rock" was used, such as at Ritchie Mines in Macfarlan in Ritchie County, West Virginia from 1852 to 1873. In 1876, asphalt-based paving was used to pave Pennsylvania Avenue in Washington DC, in time for the celebration of the national centennial.[63] In the horse-drawn era, streets were unpaved and covered with dirt or gravel. However, that produced uneven wear, opened new hazards for pedestrians and made for dangerous potholes for bicycles and for motor vehicles. Manhattan alone had 130,000 horses in 1900, pulling streetcars, wagons, and carriages, and leaving their waste behind. They were not fast, and pedestrians could dodge and scramble their way across the crowded streets. Small towns continued to rely on dirt and gravel, but larger cities wanted much better streets. They looked to wood or granite blocks by the 1850s.[64] In 1890, a third of Chicago's 2000 miles of streets were paved, chiefly with wooden blocks, which gave better traction than mud. Brick surfacing was a good compromise, but even better was asphalt paving, which was easy to install and to cut through to get at sewers. With London and Paris serving as models, Washington laid 400,000 square yards of asphalt paving by 1882; it became the model for Buffalo, Philadelphia and elsewhere. By the end of the century, American cities boasted 30 million square yards of asphalt paving, well ahead of brick.[65] The streets became faster and more dangerous so electric traffic lights were installed. Electric trolleys (at 12 miles per hour) became the main transportation service for middle class shoppers and office workers until they bought automobiles after 1945 and commuted from more distant suburbs in privacy and comfort on asphalt highways.[66]

See also: Bitumount and History of the petroleum industry in Canada (oil sands and heavy oil)

Canada has the world's largest deposit of natural bitumen in the Athabasca oil sands, and Canadian First Nations along the Athabasca River had long used it to waterproof their canoes. In 1719, a Cree named Wa-Pa-Su brought a sample for trade to Henry Kelsey of the Hudson’s Bay Company, who was the first recorded European to see it. However, it wasn't until 1787 that fur trader and explorer Alexander MacKenzie saw the Athabasca oil sands and said, "At about 24 miles from the fork (of the Athabasca and Clearwater Rivers) are some bituminous fountains into which a pole of 20 feet long may be inserted without the least resistance."[21]

The value of the deposit was obvious from the start, but the means of extracting the bitumen was not. The nearest town, Fort McMurray, Alberta, was a small fur trading post, other markets were far away, and transportation costs were too high to ship the raw bituminous sand for paving. In 1915, Sidney Ells of the Federal Mines Branch experimented with separation techniques and used the product to pave 600 feet of road in Edmonton, Alberta. Other roads in Alberta were paved with material extracted from oil sands, but it was generally not economic. During the 1920s Dr. Karl A. Clark of the Alberta Research Council patented a hot water oil separation process and entrepreneur Robert C. Fitzsimmons[67] built the Bitumount oil separation plant, which between 1925 and 1958 produced up to 300 barrels (50 m3) per day of bitumen using Dr. Clark's method. Most of the bitumen was used for waterproofing roofs, but other uses included fuels, lubrication oils, printers ink, medicines, rust- and acid-proof paints, fireproof roofing, street paving, patent leather, and fence post preservatives.[21] Eventually Fitzsimmons ran out of money and the plant was taken over by the Alberta government. Today the Bitumount plant is a Provincial Historic Site.[68]

Bitumen was used in early photographic technology. In 1826 or 1827, it was used by French scientist Joseph Nicéphore Niépce to make the oldest surviving photograph from nature. The bitumen was thinly coated onto a pewter plate which was then exposed in a camera. Exposure to light hardened the bitumen and made it insoluble, so that when it was subsequently rinsed with a solvent only the sufficiently light-struck areas remained. Many hours of exposure in the camera were required, making bitumen impractical for ordinary photography, but from the 1850s to the 1920s it was in common use as a photoresist in the production of printing plates for various photomechanical printing processes.[69][70]

Bitumen was the nemesis of many artists during the 19th century. Although widely used for a time, it ultimately proved unstable for use in oil painting, especially when mixed with the most common diluents, such as linseed oil, varnish and turpentine. Unless thoroughly diluted, bitumen never fully solidifies and will in time corrupt the other pigments with which it comes into contact. The use of bitumen as a glaze to set in shadow or mixed with other colors to render a darker tone resulted in the eventual deterioration of many paintings, for instance those of Delacroix. Perhaps the most famous example of the destructiveness of bitumen is Théodore Géricault's Raft of the Medusa (1818–1819), where his use of bitumen caused the brilliant colors to degenerate into dark greens and blacks and the paint and canvas to buckle.[71]

The vast majority of refined asphalt is used in construction: primarily as a constituent of products used in paving and roofing applications. According to the requirements of the end use, asphalt is produced to specification. This is achieved either by refining or blending. It is estimated that the current world use of asphalt is approximately 102 million tonnes per year. Approximately 85% of all the asphalt produced is used as the binder in asphalt concrete for roads. It is also used in other paved areas such as airport runways, car parks and footways. Typically, the production of asphalt concrete involves mixing fine and coarse aggregates such as sand, gravel and crushed rock with asphalt, which acts as the binding agent. Other materials, such as recycled polymers (e.g., rubber tyres), may be added to the asphalt to modify its properties according to the application for which the asphalt is ultimately intended.

A further 10% of global asphalt production is used in roofing applications, where its waterproofing qualities are invaluable. The remaining 5% of asphalt is used mainly for sealing and insulating purposes in a variety of building materials, such as pipe coatings, carpet tile backing and paint. Asphalt is applied in the construction and maintenance of many structures, systems, and components, such as the following:

Main article: Asphalt concrete

The largest use of asphalt is for making asphalt concrete for road surfaces; this accounts for approximately 85% of the asphalt consumed in the United States. Asphalt concrete pavement mixes are typically composed of 5% asphalt cement and 95% aggregates (stone, sand, and gravel). Due to its highly viscous nature, asphalt cement must be heated so it can be mixed with the aggregates at the asphalt mixing facility. The temperature required varies depending upon characteristics of the asphalt and the aggregates, but warm-mix asphalt technologies allow producers to reduce the temperature required. There are about 4,000 asphalt concrete mixing plants in the US, and a similar number in Europe.[72]

When maintenance is performed on asphalt pavements, such as milling to remove a worn or damaged surface, the removed material can be returned to a facility for processing into new pavement mixtures. The asphalt in the removed material can be reactivated and put back to use in new pavement mixes.[73] With some 95% of paved roads being constructed of or surfaced with asphalt,[74] a substantial amount of asphalt pavement material is reclaimed each year. According to industry surveys conducted annually by the Federal Highway Administration and the National Asphalt Pavement Association, more than 99% of the asphalt removed each year from road surfaces during widening and resurfacing projects is reused as part of new pavements, roadbeds, shoulders and embankments.[75]

Asphalt concrete paving is widely used in airports around the world. Due to the sturdiness and ability to be repaired quickly, it is widely used for runways.

Further information: Fibre mastic asphalt

Mastic asphalt is a type of asphalt that differs from dense graded asphalt (asphalt concrete) in that it has a higher asphalt (binder) content, usually around 7–10% of the whole aggregate mix, as opposed to rolled asphalt concrete, which has only around 5% asphalt. This thermoplastic substance is widely used in the building industry for waterproofing flat roofs and tanking underground. Mastic asphalt is heated to a temperature of 210 °C (410 °F) and is spread in layers to form an impervious barrier about 20 millimeters (0.8 inches) thick.

A number of technologies allow asphalt to be mixed at much lower temperatures. These involve mixing with petroleum solvents to form "cutbacks" with reduced melting point or mixing with water to turn the asphalt into an emulsion. Asphalt emulsions contain up to 70% asphalt and typically less than 1.5% chemical additives. There are two main types of emulsions with different affinity for aggregates, cationic and anionic. Asphalt emulsions are used in a wide variety of applications. Chipseal involves spraying the road surface with asphalt emulsion followed by a layer of crushed rock, gravel or crushed slag. Slurry seal involves the creation of a mixture of asphalt emulsion and fine crushed aggregate that is spread on the surface of a road. Cold-mixed asphalt can also be made from asphalt emulsion to create pavements similar to hot-mixed asphalt, several inches in depth, and asphalt emulsions are also blended into recycled hot-mix asphalt to create low-cost pavements.

Main article: Synthetic crude oil See also: Petroleum production in Canada

Synthetic crude oil, also known as syncrude, is the output from a bitumen upgrader facility used in connection with oil sand production in Canada. Bituminous sands are mined using enormous (100 ton capacity) power shovels and loaded into even larger (400 ton capacity) dump trucks for movement to an upgrading facility. The process used to extract the bitumen from the sand is a hot water process originally developed by Dr. Karl Clark of the University of Alberta during the 1920s. After extraction from the sand, the bitumen is fed into a bitumen upgrader which converts it into a light crude oil equivalent. This synthetic substance is fluid enough to be transferred through conventional oil pipelines and can be fed into conventional oil refineries without any further treatment. By 2015 Canadian bitumen upgraders were producing over 1 million barrels (160×10^3 m3) per day of synthetic crude oil, of which 75% was exported to oil refineries in the United States.[76]

In Alberta, five bitumen upgraders produce synthetic crude oil and a variety of other products: The Suncor Energy upgrader near Fort McMurray, Alberta produces synthetic crude oil plus diesel fuel; the Syncrude Canada, Canadian Natural Resources, and Nexen upgraders near Fort McMurray produce synthetic crude oil; and the Shell Scotford Upgrader near Edmonton produces synthetic crude oil plus an intermediate feedstock for the nearby Shell Oil Refinery.[77] A sixth upgrader, under construction in 2015 near Redwater, Alberta, will upgrade half of its crude bitumen directly to diesel fuel, with the remainder of the output being sold as feedstock to nearby oil refineries and petrochemical plants.[78]

See also: Western Canadian Select

Canadian bitumen does not differ substantially from oils such as Venezuelan extra-heavy and Mexican heavy oil in chemical composition, and the real difficulty is moving the extremely viscous bitumen through oil pipelines to the refinery. Many modern oil refineries are extremely sophisticated and can process non-upgraded bitumen directly into products such as gasoline, diesel fuel, and refined asphalt without any preprocessing. This is particularly common in areas such as the US Gulf coast, where refineries were designed to process Venezuelan and Mexican oil, and in areas such as the US Midwest where refineries were rebuilt to process heavy oil as domestic light oil production declined. Given the choice, such heavy oil refineries usually prefer to buy bitumen rather than synthetic oil because the cost is lower, and in some cases because they prefer to produce more diesel fuel and less gasoline.[77] By 2015 Canadian production and exports of non-upgraded bitumen exceeded that of synthetic crude oil at over 1.3 million barrels (210×10^3 m3) per day, of which about 65% was exported to the United States.[76]

Because of the difficulty of moving crude bitumen through pipelines, non-upgraded bitumen is usually diluted with natural-gas condensate in a form called dilbit or with synthetic crude oil, called synbit. However, to meet international competition, much non-upgraded bitumen is now sold as a blend of multiple grades of bitumen, conventional crude oil, synthetic crude oil, and condensate in a standardized benchmark product such as Western Canadian Select. This sour, heavy crude oil blend is designed to have uniform refining characteristics to compete with internationally marketed heavy oils such as Mexican Mayan or Arabian Dubai Crude.[77]

Asphalt was used starting in the 1960s as an hydrophobic matrix aiming to encapsulate radioactive waste such as medium-activity salts (mainly soluble sodium nitrate and sodium sulfate) produced by the reprocessing of spent nuclear fuels or radioactive sludges from sedimentation ponds.[79][80] Bituminised radioactive waste containing highly radiotoxic alpha-emitting transuranic elements from nuclear reprocessing plants have been produced at industrial scale in France, Belgium and Japan, but this type of waste conditioning has been abandoned because operational safety issues (risks of fire, as occurred in a bituminisation plant at Tokai Works in Japan)[81][82] and long-term stability problems related to their geological disposal in deep rock formations. One of the main problem is the swelling of asphalt exposed to radiation and to water. Asphalt swelling is first induced by radiation because of the presence of hydrogen gas bubbles generated by alpha and gamma radiolysis.[83][84] A second mechanism is the matrix swelling when the encapsulated hygroscopic salts exposed to water or moisture start to rehydrate and to dissolve. The high concentration of salt in the pore solution inside the bituminised matrix is then responsible for osmotic effects inside the bituminised matrix. The water moves in the direction of the concentrated salts, the asphalt acting as a semi-permeable membrane. This also causes the matrix to swell. The swelling pressure due to osmotic effect under constant volume can be as high as 200 bar. If not properly managed, this high pressure can cause fractures in the near field of a disposal gallery of bituminised medium-level waste. When the bituminised matrix has been altered by swelling, encapsulated radionuclides are easily leached by the contact of ground water and released in the geosphere. The high ionic strength of the concentrated saline solution also favours the migration of radionuclides in clay host rocks. The presence of chemically reactive nitrate can also affect the redox conditions prevailing in the host rock by establishing oxidizing conditions, preventing the reduction of redox-sensitive radionuclides. Under their higher valences, radionuclides of elements such as selenium, technetium, uranium, neptunium and plutonium have a higher solubility and are also often present in water as non-retarded anions. This makes the disposal of medium-level bituminised waste very challenging.

Different type of asphalt have been used: blown bitumen (partly oxidized with air oxygen at high temperature after distillation, and harder) and direct distillation bitumen (softer). Blown bitumens like Mexphalte, with a high content of saturated hydrocarbons, are more easily biodegraded by microorganisms than direct distillation bitumen, with a low content of saturated hydrocarbons and a high content of aromatic hydrocarbons.[85]

Concrete encapsulation of radwaste is presently considered a safer alternative by the nuclear industry and the waste management organisations.

Roofing shingles account for most of the remaining asphalt consumption. Other uses include cattle sprays, fence-post treatments, and waterproofing for fabrics. Asphalt is used to make Japan black, a lacquer known especially for its use on iron and steel, and it is also used in paint and marker inks by some exterior paint supply companies to increase the weather resistance and permanence of the paint or ink, and to make the color darker.[86] Asphalt is also used to seal some alkaline batteries during the manufacturing process.

Typical asphalt plant for making asphalt

About 40,000,000 tons were produced in 1984.[needs update] It is obtained as the "heavy" (i.e., difficult to distill) fraction. Material with a boiling point greater than around 500 °C is considered asphalt. Vacuum distillation separates it from the other components in crude oil (such as naphtha, gasoline and diesel). The resulting material is typically further treated to extract small but valuable amounts of lubricants and to adjust the properties of the material to suit applications. In a de-asphalting unit, the crude asphalt is treated with either propane or butane in a supercritical phase to extract the lighter molecules, which are then separated. Further processing is possible by "blowing" the product: namely reacting it with oxygen. This step makes the product harder and more viscous.[5]

Asphalt is typically stored and transported at temperatures around 150 °C (302 °F). Sometimes diesel oil or kerosene are mixed in before shipping to retain liquidity; upon delivery, these lighter materials are separated out of the mixture. This mixture is often called "bitumen feedstock", or BFS. Some dump trucks route the hot engine exhaust through pipes in the dump body to keep the material warm. The backs of tippers carrying asphalt, as well as some handling equipment, are also commonly sprayed with a releasing agent before filling to aid release. Diesel oil is no longer used as a release agent due to environmental concerns.

Main article: Oil sands

Naturally occurring crude bitumen impregnated in sedimentary rock is the prime feed stock for petroleum production from "oil sands", currently under development in Alberta, Canada. Canada has most of the world's supply of natural bitumen, covering 140,000 square kilometres[14] (an area larger than England), giving it the second-largest proven oil reserves in the world. The Athabasca oil sands are the largest bitumen deposit in Canada and the only one accessible to surface mining, although recent technological breakthroughs have resulted in deeper deposits becoming producible by in situ methods. Because of oil price increases after 2003, producing bitumen became highly profitable, but as a result of the decline after 2014 it became uneconomic to build new plants again. By 2014, Canadian crude bitumen production averaged about 2.3 million barrels (370,000 m3) per day and was projected to rise to 4.4 million barrels (700,000 m3) per day by 2020.[15] The total amount of crude bitumen in Alberta that could be extracted is estimated to be about 310 billion barrels (50×10^9 m3),[8] which at a rate of 4,400,000 barrels per day (700,000 m3/d) would last about 200 years.

Main articles: Peak oil, Global warming, and Bioasphalt

Although uncompetitive economically, asphalt can be made from nonpetroleum-based renewable resources such as sugar, molasses and rice, corn and potato starches. Asphalt can also be made from waste material by fractional distillation of used motor oil, which is sometimes otherwise disposed of by burning or dumping into landfills. Use of motor oil may cause premature cracking in colder climates, resulting in roads that need to be repaved more frequently.[87]

Nonpetroleum-based asphalt binders can be made light-colored. Lighter-colored roads absorb less heat from solar radiation, reducing their contribution to the urban heat island effect.[88] Parking lots that use asphalt alternatives are called green parking lots.

Selenizza is a naturally occurring solid hydrocarbon bitumen found in native deposits in Selenice, in Albania, the only European asphalt mine still in use. The bitumen is found in the form of veins, filling cracks in a more or less horizontal direction. The bitumen content varies from 83% to 92% (soluble in carbon disulphide), with a penetration value near to zero and a softening point (ring and ball) around 120 °C. The insoluble matter, consisting mainly of silica ore, ranges from 8% to 17%.

Albanian bitumen extraction has a long history and was practiced in an organized way by the Romans. After centuries of silence, the first mentions of Albanian bitumen appeared only in 1868, when the Frenchman Coquand published the first geological description of the deposits of Albanian bitumen. In 1875, the exploitation rights were granted to the Ottoman government and in 1912, they were transferred to the Italian company Simsa. Since 1945, the mine was exploited by the Albanian government and from 2001 to date, the management passed to a French company, which organized the mining process for the manufacture of the natural bitumen on an industrial scale.[89]

Today the mine is predominantly exploited in an open pit quarry but several of the many underground mines (deep and extending over several km) still remain viable. Selenizza is produced primarily in granular form, after melting the bitumen pieces selected in the mine.

Selenizza[90] is mainly used as an additive in the road construction sector. It is mixed with traditional asphalt to improve both the viscoelastic properties and the resistance to ageing. It may be blended with the hot asphalt in tanks, but its granular form allows it to be fed in the mixer or in the recycling ring of normal asphalt plants. Other typical applications include the production of mastic asphalts for sidewalks, bridges, car-parks and urban roads as well as drilling fluid additives for the oil and gas industry. Selenizza is available in powder or in granular material of various particle sizes and is packaged in sacks or in thermal fusible polyethylene bags.

A life-cycle assessment study of the natural selenizza compared with petroleum asphalt has shown that the environmental impact of the selenizza is about half the impact of the road asphalt produced in oil refineries in terms of carbon dioxide emission.[91]

People can be exposed to asphalt in the workplace by breathing in fumes or skin absorption. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit of 5 mg/m3 over a 15-minute period.[92]

Asphalt is basically an inert material that must be heated or diluted to a point where it becomes workable for the production of materials for paving, roofing, and other applications. In examining the potential health hazards associated with asphalt, the International Agency for Research on Cancer (IARC) determined that it is the application parameters, predominantly temperature, that affect occupational exposure and the potential bioavailable carcinogenic hazard/risk of the asphalt emissions.[93] In particular, temperatures greater than 199 °C (390 °F), were shown to produce a greater exposure risk than when asphalt was heated to lower temperatures, such as those typically used in asphalt pavement mix production and placement.[94] IARC has classified asphalt as a Class 2B possible carcinogen.

An asphalt mixing plant for hot aggregate
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