Asphalt

As shown in this cross-section, many older roadways are smoothed by applying a thin layer of asphalt concrete to the existing portland cement concrete.

Base layer of asphalt concrete in a road under construction

Machine laying asphalt concrete, fed by a dump truck.

Asphalt concrete, normally known simply as asphalt, is a composite material commonly used for construction of pavement, highways and parking lots. It consists of asphalt binder and mineral aggregate mixed together then laid down in layers and compacted. Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (1600 × 1200 pixel, file size: 1 MB, MIME type: image/jpeg) I, the copyright holder of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU... Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (1600 × 1200 pixel, file size: 1 MB, MIME type: image/jpeg) I, the copyright holder of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU... Image File history File linksMetadata Asphalt_on_concrete. ... Image File history File linksMetadata Asphalt_on_concrete. ... This article is about the construction material. ... Image File history File links Download high resolution version (1097x851, 881 KB)Shot by Estr4ng3d, Helwan-Korayimat Road (Cairo, Egypt) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Download high resolution version (1097x851, 881 KB)Shot by Estr4ng3d, Helwan-Korayimat Road (Cairo, Egypt) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Download high-resolution version (1400x904, 148 KB) The asphalt laying machine is fed by a dumpster for the first layer of asphalt on the Kabul-Kandahar Road. ... Image File history File links Download high-resolution version (1400x904, 148 KB) The asphalt laying machine is fed by a dumpster for the first layer of asphalt on the Kabul-Kandahar Road. ... Base layer of asphalt concrete in a road under construction. ... A cloth of woven carbon fiber filaments, a common element in composite materials Composite materials (or composites for short) are engineered materials made from two or more constituent materials with significantly different physical or chemical properties and which remain separate and distinct within the finished structure. ... This article needs additional references or sources to facilitate its verification. ... This article or section does not cite any references or sources. ... Parking lot showing diagonal parking pattern designed for one-way traffic. ... A binder is a material used to bind together two or more other materials in mixtures. ... Limestone Quarry Construction aggregate, or simply, aggregate, is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, slag, and recycled concrete. ...

Mixing of asphalt and aggregate is accomplished in one of several ways:

• Hot mix asphalt concrete (commonly abbreviated as HMAC or HMA) is produced by heating the asphalt in order to decrease its viscosity and drying the aggregate to remove moisture from it prior to mixing. Mixing is generally performed with the aggregate at about 300 °F (roughly 150 °C), and the asphalt cement at 200 °F (95 °C). Paving and compaction must be performed while the asphalt is sufficiently hot. In many states paving is restricted to summer months because in winter the compacted base will cool the asphalt too much before it is packed to the optimal air content. HMAC is the form of asphalt concrete most commonly used on highly trafficked pavements such as those on major highways and airfields.
• Warm mix asphalt concrete (commonly abbreviated as WMA or WAM) is produced by adding either zeolites, waxes, or asphalt emulsions to the mix. This allows significantly lower mixing and laying temperatures and results in lower consumption of fossil fuels, thus releasing less carbon dioxide, aerosols and vapours. Not only are working conditions clearly improved, but the lower laying-temperature also leads to more rapid availability of the surface for use, which is important for construction sites with critical time schedules. The usage of these additives in hot mixed asphalt (see above) may lead to easier compaction and allow cold weather paving or longer hauls etc.
• Cold mix asphalt concrete is produced by emulsifying the asphalt in water with (essentially) soap prior to mixing with the aggregate. While in its emulsified state the asphalt is less viscous and the mixture is easy to work and compact. The emulsion will break after enough water evaporates and the cold mix will, ideally, take on the properties of cold HMAC. Cold mix is commonly used as a patching material and on lesser trafficked service roads.
• Cut-back asphalt concrete is produced by dissolving the binder in kerosene or another lighter fraction of petroleum prior to mixing with the aggregate. While in its dissolved state the asphalt is less viscous and the mix is easy to work and compact. After the mix is laid down the lighter fraction evaporates. Due to the resulting air pollution, cut-backs have been illegal in the U.S. since the 1970s. They are still widely used in Europe and the rest of the world, especially for recycling old asphalt pavement.
• Mastic asphalt concrete or sheet asphalt is produced by heating hard grade blown bitumen (oxidation) in a green cooker (mixer) until it has become a viscous liquid after which the aggregate mix is then added.

The bitumen aggregate mixture is cooked (matured) for around 6-8 hours and once it is ready the mastic asphalt mixer is transported to the work site where experienced layers empty the mixer and either machine or hand lay the mastic asphalt contents on to the road. Mastic asphalt concrete is generally laid to a thickness of around 20-30 mm for footpath and road applications and around 10 mm for flooring or roof applications.

In addition to the asphalt and aggregate, additives, such as polymers, and antistripping agents may be added to improve the properties of the final product.

• Natural asphalt concrete can be found in some parts of the world where rock near the surface has been impregnated with upwelling asphalt.

The terms asphalt concrete, bituminous asphalt concrete, etc., are typically used only in engineering jargon. Asphalt pavements are often called just asphalt by laypersons who tend to associate the term concrete with Portland cement concrete only. The engineering definition of concrete is any composite material composed of mineral aggregate stuck together with a binder, whether that binder is Portland cement, asphalt or even epoxy. Informally, asphalt concrete is also referred to as blacktop. This article is about the American English usage of pavement as the durable surfacing of roads and walkways. ... This article or section does not cite any references or sources. ... For other uses, see Airport (disambiguation). ... Zeolite The micro-porous molecular structure of a zeolite, ZSM-5 Zeolites (Greek, zein, to boil; lithos, a stone) are minerals that have a micro-porous structure. ... candle wax This page is about the substance. ... A. Two immisicible liquids, not emulsified; B. An emulsion of Phase B dispersed in Phase A; C. The unstable emulsion progressively separates; D. The surfactant (purple outline) positions itself on the interfaces between Phase A and Phase B, stabilizing the emulsion An emulsion is a mixture of two immiscible (unblendable... Fossil fuels are hydrocarbons, primarily coal and petroleum (fuel oil or natural gas), formed from the fossilized remains of dead plants and animals[1] by exposure to heat and pressure in the Earths crust over hundreds of millions of years[2]. The theory that hydrocarbons were formed from these... In order to meet Wikipedias quality standards, this article requires cleanup. ... Particulates, alternatively referred to as particulate matter (PM), aerosols or fine particles, are tiny particles of solid or liquid suspended in a gas. ... SOAP (see below for name and origins) is a protocol for exchanging XML-based messages over computer networks, normally using HTTP/HTTPS. SOAP forms the foundation layer of the Web services stack, providing a basic messaging framework that more abstract layers can build on. ... Kerosene or paraffin oil (British English, not to be confused with the waxy solid also called paraffin wax or just paraffin) is a flammable hydrocarbon liquid. ... Pumpjack pumping an oil well near Lubbock, Texas Ignacy Łukasiewicz - inventor of the refining of kerosene from crude oil. ... Air pollution is a chemical, physical (e. ... The 1970s decade refers to the years from 1970 to 1979, also called The Seventies. ... This article needs additional references or sources to facilitate its verification. ... Ewer from Iran, dated 1180-1210CE. Composed of brass worked in repoussé and inlaid with silver and bitumen. ... The most fundamental reactions in chemistry are the redox processes. ... Binomial name L. Mastic (Pistacia lentiscus) is an evergreen shrub or small tree growing to 3–4 m tall, mainly cultivated for its aromatic resin on the Greek island of Chios,[1]. It is native throughout the Mediterranean region, from Morocco and Iberia at the east through southern France and... The term asphalt is often used as an abbreviation for asphalt concrete. ... A polymer is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... A tar pit, or more properly asphalt pit, is a geological occurrence where subterranean bitumen leaks to the surface, creating a large puddle, pit, or lake of asphalt. ... Engineering is the design, analysis, and/or construction of works for practical purposes. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Base layer of asphalt concrete in a road under construction. ... This article is about the construction material. ... A cloth of woven carbon fiber filaments, a common element in composite materials Composite materials (or composites for short) are engineered materials made from two or more constituent materials with significantly different physical or chemical properties and which remain separate and distinct within the finished structure. ... Sampling fast set Portland cement Portland cement is the most common type of cement in general usage, as it is a basic ingredient of concrete, mortar and plaster. ... In chemistry, epoxy or polyepoxide is a thermosetting epoxide polymer that cures (polymerizes and crosslinks) when mixed with a catalyzing agent or hardener. Most common epoxy resins are produced from a reaction between epichlorohydrin and bisphenol-A. The first commercial attempts to prepare resins from epichlorohydrin occurred in 1927 in...

Asphalt concrete is often touted as being 100% recyclable. Several in-place recycling techniques have been developed to rejuvenate oxidized binders and remove cracking, although the recycled material is generally not very water-tight or smooth and should be overlaid with a new layer of asphalt concrete. Asphalt concrete that is removed from a pavement is usually stockpiled for later use as a base course material. This reclaimed material, commonly known by the acronym 'RAP' for recycled or reclaimed asphalt pavement, is crushed to a consistent gradation and added to the HMA mixing process. Very little asphalt concrete is actually disposed of in landfills. Sometimes waste materials, such as rubber from old tires, are added to asphalt concrete as is the case with rubberized asphalt, but there is a concern that the hybrid material may not be recyclable. Base course refers to the sub-base layer of an asphalt roadway. ... Albury landfill, Surrey, England A landfill, also known as a dump, is a site for the disposal of waste materials by burial and is the oldest form of waste treatment. ... This does not cite any references or sources. ... For a table of tire companies, see List of tire companies. ... Rubberized asphalt is pavement material that consists of regular asphalt concrete mixed with crumb rubber -- ground, used tires that would otherwise be discarded or take up space in landfills. ... The international symbol for recycling. ...

Asphalt deterioration can include alligator cracks, potholes, upheaval, raveling, rutting, shoving, stripping, and grade depressions. The city of Los Angeles is famous for its large potholes. ...

Asphalt concrete pavements—especially those at airfields—are sometimes called tarmac for historical reasons, although they do not contain tar and are not constructed using the macadam process. For other uses, see Airport (disambiguation). ... A close-up view of some freshly-laid tarmac. ... Tar can be produced from corn stalks by heating in a microwave. ... Macadam is a type of road construction pioneered by John Loudon McAdam in the early 1800s. ...

See also

• Asphalt
• Free floating screed
• Plastic armour
• Tarmac

Base layer of asphalt concrete in a road under construction. ... The free floating screed is a device pioneered by Barber Greene Company in the 1930s that revolutionized the asphalt paving process. ... Plastic armour is a type of vehicle armour developed for merchant ships by the British Admiralty in 1940. ... A close-up view of some freshly-laid tarmac. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... It has been suggested that German Autobahns be merged into this article or section. ... This page meets Wikipedias criteria for speedy deletion. ... An autoroute. ... Autostrada is the Italian word for motorways/freeways, but is used in several countries including Albania, Lithuania, Poland, Egypt, Israel, and Romania. ... Signpost to an Autostrasse (this one leads to the A1L motorroad leading out of central Zürich). ... Auto-estrada is the Portuguese word for motorways/freeways. ... This article needs additional references or sources for verification. ... For specific systems, such as the Autobahns of Germany, see list of highway systems with full control of access and no cross traffic. ... South section of North-South Expressway near Pedas-Linggi, Negeri Sembilan, facing towards Kuala Lumpur. ... Motorway symbol in UK, France and Ireland. ... A highway is a major road within a city, or linking several cities together. ... 2+1 road with cable barrier near Linköping, Sweden. ... Divided Highway is the fourteenth studio album by American rock band The Doobie Brothers, released in 2003. ... This article needs additional references or sources for verification. ... The sign for FM 1957, a Farm-to-Market road near San Antonio, Texas. ... This article or section does not cite any references or sources. ... Harden Parkway in Salinas, CA. For other uses, see Parkway (disambiguation). ... A super two or super two-lane highway is a two-lane surface road built to high standards, typically including partial control of access, occasional passing lanes and hard shoulders. ... This article does not cite any references or sources. ... The Champs Elysees in Paris, France. ... A frontage road for U.S. Highway 71 (a freeway) near Carthage, Missouri. ... Mountain road with hairpin turns in the French Alps For other uses, see Road (disambiguation). ... A city-centre street in Frankfurt, Germany A residential street in Cambridge, Massachusetts, USA A street is a public thoroughfare in the built environment. ... An Alley in Melbourne A gate to an alley in Annapolis, Maryland An alley or alleyway is a narrow, pedestrian lane found in urban areas which usually run between or behind buildings. ... For the musical group, see Cul de Sac (group). ... Driveway to a farm A driveway is a type of private road for local access to one or a small group of structures, and maintained by an individual or group. ... The word lane has two meanings: a portion of a paved roadway which is intended for a single line of vehicles and is marked by white or yellow lines. ... This early German Autobahn uses a dual carriageway design. ... High-capacity freeway interchange in Los Angeles, California. ... Fort Jackson The range road is a term often used in the military for the road linking up the rifle ranges. ... A roundabout, rotary, or gyratory circus is a type of road junction (or traffic calming device) at which traffic streams circularly around a central island after first yielding to the circulating traffic. ... This article or section does not cite any references or sources. ... An old brick wall in English bond laid with alternating courses of headers and A brick is a block of ceramic material used in masonry construction and sized to be layed with one hand using mortar. ... A cobblestone-covered street Cobblestones are stones used in the pavement of early streets. ... Concrete being poured, raked and vibrated into place in residential construction in Toronto, Ontario, Canada. ... This article does not cite its references or sources. ... Dirt road is a common term for an unpaved road. ... A gravel road is a road which is paved with small pieces of broken rock, called gravel. ... Ice Road in northern British Columbia, Canada Ice roads are temporary highways formed by using frozen rivers and lake surfaces. ... Macadam is a type of road construction pioneered by John Loudon McAdam in the early 1800s. ... Ewer from Iran, dated 1180-1210CE. Composed of brass worked in repoussé and inlaid with silver and bitumen. ... A plank road or puncheon is a dirt path or road covered with a series of planks, similar to the wooden sidewalks one would see in a Western movie. ... A close-up view of some freshly-laid tarmac. ... Winter roads are temporary highways carved out of snow and ice. ...

External links

• Warm mix asphalt - Evotherm
• Warm mix asphalt - aspha-min
• Warm mix asphalt - Wam Foam