I walk by an apartment complex which is getting its parking lot repaved with asphalt. I have parked on many asphalt parking lots and driven on many asphalt roads. Sometimes, they seem smoother than the concrete ones. It looks like quite a process to repave with asphalt which involves rolling, spreading and mashing machines. The parking lot needs to be evacuated to get a pristine repaving. I am on the board of the homeowners’ association where I live. We have had to have our parking lot repaved more than once. If you get heavy trucks rolling over the surface, it develops ruts. The parking lot right in front of the dumpster where the heavy waste disposal truck arrived weekly to dump the trash developed a very deep, serious rut. It can be a very expensive problem to fix. I am grateful there are experts who know how to repair such damage, but it doesn’t always come cheap. Asphalt can be a very functional product. Let’s learn more about it.
According to Wikipedia, asphalt — also known as bitumen — is a sticky, black, 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. The word is derived from the Ancient Greek ásphaltos. The largest natural deposit of asphalt in the world — estimated to contain 10 million tons — is Pitch Lake located in La Brea in southwest Trinidad — Antilles island located on the northeastern coast of Venezuela, within the Siparia Regional Corporation. The region of Siparia is a Regional Corporation, which handles local government functions. The Siparia Regional Corporation is headquartered in Siparia, a region of Trinidad and Tobago in the southwestern portion of the island.
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.
In material sciences and engineering, the terms "asphalt" and "bitumen" are often used interchangeably to mean both natural and manufactured forms of the substance, although there is regional variation as to which term is most common. Worldwide, geologists tend to favor the term "bitumen" for the naturally occurring material. For the manufactured material, which is a refined residue from the distillation process of selected crude oils, "bitumen" is the prevalent term in much of the world; however, in American English "asphalt" is more commonly used. To help avoid confusion, the phrases "liquid asphalt," "asphalt binder" or "asphalt cement" are used in the U.S. Colloquially, various forms of asphalt are sometimes referred to as "tar," as in the name of the La Brea Tar Pits, although tar is a different material.
Naturally occurring asphalt is sometimes specified by the term "crude bitumen." Its viscosity is similar to that of cold molasses, while the material obtained from the fractional distillation of crude oil boiling at 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 55,000 square miles, an area larger than England.
Asphalt properties change with temperature, which means that there is a specific range where viscosity permits adequate compaction by providing lubrication between particles during the compaction process. Low temperature prevents aggregate particles from moving, and the required density is not possible to achieve. Computer simulations of simplified model systems are able to reproduce some of asphalt's characteristic properties.
Normal composition
The components of asphalt include four main classes of compounds:
- Naphthene aromatics or naphthalene, consisting of partially hydrogenated polycyclic aromatic compounds.
- Polar aromatics, consisting of high molecular weight phenols and carboxylic acids produced by partial oxidation of the material.
- Saturated hydrocarbons; the percentage of saturated compounds in asphalt correlates with its softening point.
- Asphaltenes, consisting of high molecular weight phenols and heterocyclic 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.
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. "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 — single-sized crushed stone layers of small angular stones placed in shallow lifts and compacted thoroughly — 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.
Occurrence
The majority of asphalt used commercially is obtained from petroleum. 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 or 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 in the U.S. The Canadian province of Alberta has most of the world's reserves, in three huge deposits covering 55,000 square miles, an area larger than England or New York state. These bituminous sands contain 166 billion barrels 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.
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. Isotopic studies show the oil deposits to be about 110 million years old. 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.
Much smaller heavy oil or bitumen deposits also occur in the Uinta Basin in Utah. 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, 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.
Bitumen is similar to the organic matter in carbonaceous meterorites. However, detailed studies have shown these materials to be distinct. 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 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 kilometers and trapped into underground sand deposits left behind by ancient riverbeds and ocean beaches, thus forming the oil sands.
Ancient times
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. By the third millennium BC, refined rock asphalt was in use in the region and was used to waterproof the Great Bath in Mohenjo-daro, Pakistan.
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. The Greek historian Herodotus said hot bitumen was used as mortar in the walls of Babylon.
The 1 kilometer or 0.62 mile-long Euphrates Tunnel beneath the river Euphrates at Babylon in the time of Queen Semiramis — c. 800 BC — was reportedly constructed of burnt bricks covered with bitumen as a waterproofing agent.
Bitumen was used by ancient Egyptians to embalm mummies. 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 or Asphalt Lake.
In approximately 40 AD Dioscorides described the Dead Sea material as Judaicum bitumen and noted other places in the region where it could be found. The Sidon bitumen is thought to refer to material found at Hasbeya in Lebanon. Pliny also refers to bitumen being found in Epirus. Bitumen was a valuable strategic resource. It was the object of the first known battle for a hydrocarbon deposit — between the Seleucids and the Nabateans in 312 BC.
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, 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 that bitumen was sometimes used to adhere stone projectile points to wooden shafts. 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.
History in Continental Europe
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.
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."
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 for similar purposes." Its rise in Europe was "a sudden phenomenon," after natural deposits were found "in France at Osbann or Bas-Rhin, the Parc or Ain and the Puy-de-la-Poix or Puy-de-Dôme," although it could also be made artificially. One of the earliest uses in France was the laying of about 24,000 square yards of Seyssel asphalt at the major public square of the Place de la Concorde in 1835.
History in the United Kingdom
Among the earlier uses of bitumen in the United Kingdom was for etching. William Salmon's “Polygraphice” in 1673 provides a recipe for varnish used in etching, consisting of three ounces of virgin wax, two ounces of mastic — resin obtained from the mastic tree and one ounce of asphaltum. By the fifth edition in 1685, he had included more asphaltum recipes from other sources.
The first British patent for the use of asphalt was "Cassell's patent asphalte or bitumen" in 1834. Then on November 25, 1837, Richard Tappin Claridge patented the use of Seyssel asphalt — patent #7849 — for use in asphalte pavement, 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. 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."
Claridge obtained a patent in Scotland March 27, 1838 and obtained a patent in Ireland on April 23, 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 Co. — 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 Co. — 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." "By the end of 1838, at least two other companies, Robinson's and the Bastenne company, were in production," 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." The Bonnington Chemical Works manufactured asphalt using coal tar, and by 1839 had installed it in Bonnington.
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. On the London stock market, 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."
In 1914, Claridge's Company entered into a joint venture to produce tar-bound macadam, with materials manufactured through a subsidiary company called Clarmac Roads Ltd. 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. However, the First World War ruined the Clarmac Co., which entered into liquidation in 1915. The failure of Clarmac Roads Ltd. had a flow-on effect to Claridge's company, which was itself compulsorily wound up, ceasing operations in 1917, having invested a substantial amount of funds into the new venture, both at the outset and in a subsequent attempt to save the Clarmac Co.
Bitumen was thought in 19th century Britain to contain chemicals with medicinal properties. Extracts from bitumen were used to treat catarrh — inflammation of the mucous membranes in one of the airways or cavities of the body — and some forms of asthma and as a remedy against worms, especially the tapeworm.
History in the United States
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. 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, D.C. in time for the celebration of the national centennial.
In the horse-drawn era, U.S. streets were mostly unpaved and covered with dirt or gravel. Especially where mud or trenching often made streets difficult to pass, pavements were sometimes made of diverse materials including wooden planks, cobblestones or other stone blocks or bricks. Unpaved roads produced uneven wear and hazards for pedestrians. In the late 19th century with the rise of the popular bicycle, bicycle clubs were important in pushing for more general pavement of streets. Advocacy for pavement increased in the early 20th century with the rise of the automobile. Asphalt gradually became an ever more common method of paving. St. Charles Avenue in New Orleans was paved its whole length with asphalt by 1889.
In 1900 Manhattan alone had 130,000 horses, pulling streetcars, wagons and carriages, 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. In 1890, a third of Chicago's 2,000 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. 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.
History in Canada
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 Co., 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."
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 built the Bitumount oil separation plant, which between 1925 and 1958 produced up to 300 barrels 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. 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.
“View from the Window at Le Gras” is a heliographic image and the oldest surviving camera photograph of nature. The original plate is on the left and the colorized reoriented enhancement is on the right. The photo was taken from a second-story south-facing bedroom window.
Photography and art
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 — light-sensitive material used in several processes, such as photolithography and photoengraving, to form a patterned coating on a surface — in the production of printing plates for various photomechanical printing processes.
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” in 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.
Production
About 40,000,000 tons were produced in 1984. 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.
Asphalt is typically stored and transported at temperatures around 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.
Rolled 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. There are about 4,000 asphalt concrete mixing plants in the U.S. and a similar number in Europe.
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.
The weight of an asphalt pavement depends upon the aggregate type, the asphalt and the air void content. An average example in the United States is about 112 pounds per square yard, per inch of pavement thickness.
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. With some 95% of paved roads being constructed of or surfaced with asphalt, 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 or stockpiled for future use.
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.
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