Base layer of asphalt concrete in a road under construction. Asphalt concrete, normally known simply as Asphalt, is a Composite material commonly used for construction of pavement, Highways and

Asphalt (ˈæs.fɒlt (help·info)) is a sticky, black and highly viscous liquid or semi-solid that is present in most crude petroleums and in some natural deposits sometimes termed asphaltum. Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. Petroleum ( L petroleum, from Greek πετρέλαιον, lit It is most commonly modeled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase (though there is some disagreement amongst chemists regarding its structure). A colloid is a type of mechanical Mixture where one substance is dispersed evenly throughout another Asphaltenes are molecular substances that are found in Crude oil, along with Resins, Aromatic hydrocarbons and Alkanes (i A chemist is a Scientist trained in the Science of Chemistry. In U.S. terminology, asphalt (or asphalt cement) is the carefully refined residue from the distillation process of selected crude oils. Phonology North American English regional phonology In many ways compared to English English, North American English is conservative in its Phonology. Outside North America, the product is called bitumen. Bitumen is a mixture of organic Liquids that are highly Viscous, black sticky entirely soluble in Carbon disulfide, and composed primarily

The primary use of asphalt (Bitumen) is in road construction, where it is used as the glue or binder for the aggregate particles. Bitumen is a mixture of organic Liquids that are highly Viscous, black sticky entirely soluble in Carbon disulfide, and composed primarily Construction aggregate, or simply " aggregate " is a broad category of coarse particulate Material used in Construction, including The road surfacing material is usually called 'asphalt concrete' in North America or simply 'asphalt' elsewhere. The apparent interchangeability of the words 'asphalt' and 'bitumen' causes confusion outside of the road construction industry despite quite clear definitions within industry circles.

Background

Asphalt or bitumen can sometimes be confused with tar, which is a similar black thermo-plastic material produced by the destructive distillation of coal. Tar is a viscous black Liquid derived from the Destructive distillation of organic matter Destructive distillation is the process of Pyrolysis conducted in a distillation apparatus ( Retort) to allow the volatile products to be collected During the early and mid twentieth century when town gas was produced, tar was a readily available product and extensively used as the binder for road aggregates. The addition of tar to macadam roads led to the word tarmac, which is now used in common parlance to refer to road making materials. Macadam is a type of Road construction pioneered by the Scotsman John Loudon McAdam in around 1820 Tarmac (short for tarmacadam, a Portmanteau for Tar -penetration Macadam) is a type of highway surface, pioneered by John However, since the 1970s, when natural gas succeeded town gas, asphalt (bitumen) has completely overtaken the use of tar in these applications. Natural gas is a Gaseous Fossil fuel consisting primarily of Methane but including significant quantities of Ethane, Propane,

Asphalt can be separated from the other components in crude oil (such as naphtha, gasoline and diesel) by the process of fractional distillation, usually under vacuum conditions. Naphtha normally refers to a number of different flammable liquid mixtures of hydrocarbons i Diesel or Diesel fuel (ˈdiːzəl in general is any Fuel used in Diesel engines The most common is a specific fractional distillate of petroleum Fractional distillation is the separation of a mixture into its component parts or fractions such as in separating Chemical compounds by their Boiling point by heating This vacuum means "absence of matter" or "an empty area or space" for the cleaning appliance see Vacuum cleaner. A better separation can be achieved by further processing of the heavier fractions of the crude oil in a de-asphalting unit, which uses either propane or butane in a supercritical phase to dissolve the lighter molecules which are then separated. A de-asphalting unit separates the Asphalt from the rest of the crude oil residue Propane is a three- Carbon Alkane, normally a gas but compressible to a liquid that is transportable Butane, also called n -butane, is the unbranched Alkane with four Carbon Atoms CH3CH2CH2CH3 A supercritical fluid is any substance at a Temperature and Pressure above its Thermodynamic critical point. Further processing is possible by "blowing" the product: namely reacting it with oxygen. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the This makes the product harder and more viscous.

Natural deposits of asphalt include lake asphalts (primarily from the Pitch Lake in Trinidad and Tobago and Bermudez Lake in Venezuela), Gilsonite, the Dead Sea between Israel & Jordan, and Tar Sands. The Pitch Lake is a lake of natural Asphalt located at La Brea in southwest Trinidad. The Republic of Trinidad and Tobago (ˈtrɪnɪdæd ən təˈbeɪgoʊ is an archipelagic state in the southern Caribbean, lying northeast of the South American Venezuela (ˌvɛnəˈzweɪlə) officially the Bolivarian Republic of Venezuela (Spanish República Bolivariana de Venezuela) is a country on the Gilsonite is the registered Trademark for a form of natural Asphalt found in large amounts in the Uinta Basin of Utah; the non-trademarked mineral The Dead Sea (יָם הַ‏‏מֶ‏ּ‏לַ‏ח, "Sea of Salt"البَحْر المَيّت, "Dead Sea" is a salt lake between For a topic outline on this subject see List of basic Israel topics. Jordan, officially the Hashemite Kingdom of Jordan (الأردنّ al-Urdunn) is an Arab country in Southwest Asia spanning the southern

Asphalt is typically stored and transported at temperatures around 150 degrees Celsius (300 °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. Diesel or Diesel fuel (ˈdiːzəl in general is any Fuel used in Diesel engines The most common is a specific fractional distillate of petroleum Kerosene, sometimes spelled kerosine in scientific and industrial usage is a Combustible Hydrocarbon liquid 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. A dump truck or production truck is a Truck used for transporting loose material (such as Sand, Gravel, or dirt) for Construction 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 sometimes used as a release agent, although it can mix with and thereby reduce the quality of the asphalt.

Known uses

Ancient times

In the ancient Middle East, natural asphalt deposits were used for mortar between bricks and stones, ship caulking, and waterproofing. The Middle East is a Subcontinent with no clear boundaries often used as a synonym to Near East, in opposition to Far East. Mortar is a workable paste formed by mixture of Cement, Water and fine aggregate Masonry to bind construction blocks together and fill the gaps between Caulking is a process used to seal the seams in Wooden Boats or ships and riveted iron or steel ships in order to make them watertight The Persian word for asphalt is mumiya, which may be related to the English word mummy. A mummy is a Corpse whose Skin and Flesh have been preserved by either intentional or Incidental exposure to Chemicals extreme Asphalt was also used by ancient Egyptians to embalm mummies. Embalming, in most modern Cultures is the Art and Science of temporarily preserving human remains to forestall Decomposition

In the ancient Far East, natural asphalt was slowly boiled to get rid of the higher fractions, leaving a material of higher molecular weight which is thermoplastic and when layered on objects, became quite hard upon cooling. The Far East is a term often used by people in the Western world to refer to the countries of East Asia. This was used to cover scabbards and other objects that needed water-proofing. A scabbard is a Sheath for holding a Sword or other large blade Statuettes of household deities were also cast with this type of material in Japan, and probably also in China. See also List of deities A deity is a Postulated Preternatural or Supernatural Being, who is always

Poured bitumen has also been used as a damp-proof course in building. A damp-proof course (often abbreviated to DPC is a horizontal barrier in a Wall designed to prevent moisture rising through the structure by Capillary action

Rolled asphalt concrete

The largest use of asphalt is for making asphalt concrete for road surfaces and accounts for approximately 80% of the asphalt consumed in the United States. Asphalt concrete, normally known simply as Asphalt, is a Composite material commonly used for construction of pavement, Highways and The United States of America —commonly referred to as the Roofing shingles account for most of the remaining asphalt consumption. An asphalt shingle is a type of Roof shingle. They are one of the most widely used roofing covers because they are relatively inexpensive and fairly simple to install Other uses include cattle sprays, fence post treatments, and waterproofing for fabrics.

Asphalt road surface is the most widely recycled material in the US, both by gross tonnage and by percentage. According to a report issued by the Federal Highway Administration and the United States Environmental Protection Agency, 80% of the asphalt from road surfaces' that is removed each year during widening and resurfacing projects is reused as part of new roads, roadbeds, shoulders and embankments. The Federal Highway Administration ( FHWA) is a division of the United States Department of Transportation that specializes in Highway transportation

Mastic asphalt

Mastic asphalt is a type of asphalt which differs from dense graded asphalt (asphalt concrete) in that it has a higher bitumen (binder) content, usually around 7-10% of the whole aggregate mix, as opposed to roller asphalt, which has only around 5% added bitumen. Asphalt ( is a sticky black and highly viscous liquid or semi-solid that is present in most crude Petroleums and in some natural deposits sometimes termed asphaltum Asphalt concrete, normally known simply as Asphalt, is a Composite material commonly used for construction of pavement, Highways and The reaper-binder, or binder, was a farm implement that improved upon the Reaper. Another asphalt which is fast gaining global popularity is stone mastic asphalt (SMA). Stone mastic asphalt was developed in Germany in the 1960's Stone Mastic Asphalt (SMA provides a deformation resistant durable surfacing material suitable for heavily SMA's advantages over rolled asphalt is its high anti skid qualities due to its high aggregate density and the lack of void content (air pockets). Another advantage of SMA is its longer durability over alternative road asphalt surfaces, but its manufacture and application, if not controlled closely, can result in slippery road surfaces due to excess bitumen pooling (bleeding) onto the surface.

Asphalt emulsion

A number of technologies allow asphalt to be mixed at much lower temperatures. These involve mixing the asphalt with petroleum solvents to form "cutbacks" with reduced melting point or mixtures with water to turn the asphalt into an emulsion. An emulsion ( IPA: /ɪˈmʌlʃən/ is a mixture of two Immiscible (unblendable liquids 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. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge 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 or gravel. Chip Seal is a pavement surface treatment that combines a layer of Asphalt with a layer of fine aggregate. 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.

Mixing with petroleum-contaminated soil

Sometimes asphalt can be mixed with the output from low-temperature thermal desorption. NOTE This article is largely taken verbatim from the EPA's How to Evaluate Alternative Cleanup Technologies for Underground Storage Tank Sites.

Alternatives

The world has become increasingly concerned over the global climate change problem in recent years due to the pollution that is released into the atmosphere. Most of the emissions are derived primarily from burning fossil fuels. This has led to the introduction of bitumen alternatives that are more environmentally friendly and non toxic. Bitumen can now be made from non-petroleum based renewable resources such as sugar, molasses and rice, corn and potato starches etc. To further help the environment bitumen can also be made from the waste material vacuum tower bottoms produced in the process of cleaning used motor oils which helps the recycling industries, this waste is normally disposed by burning or dumping into land fills. These new non-petroleum based bitumen binders can be colored, which thereby help reduce the temperatures of road surfaces which contribute to the Urban heat island which in turn contributes to global climate change. An urban heat island ( UHI) is a metropolitan area which is significantly warmer than its surrounding rural areas For millions of people living in and around cities, heat islands are of growing concern. This phenomenon describes urban and suburban temperatures that are 2 to 10°F (1 to 6°C) hotter than nearby rural areas Elevated temperatures can impact communities by increasing peak energy demand, air conditioning costs, air pollution levels, and heat-related illness and mortality. Fortunately, there are common-sense measures that communities can take to reduce the negative effects of heat islands, such as replacing conventional black asphalt road surfaces with the new pigmentable bitumen that gives lighter colors [1] [2].

Asphalt made with vegetable oil based binders was patented by Colas SA in France in 2004 (Vegecol), Colas was originally owned by the Royal Dutch Shell [3]. [4]

A number of homeowners seeking an environmentally-friendly alternative to asphalt for paving have experimented with waste vegetable oil as a binder for driveways and parking areas in single-family applications. The earliest known test occurred in 2002 in Ohio, where the homeowner combined waste vegetable oil with dry aggregate to create a low-cost and non-polluting paving material for his 200-foot driveway. After five years, he reports the driveway is performing as well or better than petroleum-based materials.

This movement has led the Shell Oil Company (see also, Controversies surrounding Royal Dutch Shell) to pave two public roads in Norway in 2007 with the Colas vegetable-oil-based asphalt. There have been concerns over Royal Dutch Shell over environmental and health and safety related issues as well as Results of this study are still premature.

Etymology

The word asphalt is derived from the late Middle English : from French asphalte, based on late Latin asphalton, asphaltum, from Greek asphalton, asphaltos (άσφαλτος), ásphaltos, -on, akin to asphalízein to make firm, to secure.

References

See also

• Blacktop

External links

• International Chemical Safety Card 0612
• U.S EPA
• Vegetable oil based Asphalt Binders
• National Institute for Occupational Safety and Health - Asphalt Fumes