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Asphalt batch mix plant A machine laying asphalt concrete, fed from a dump truck. Asphalt concrete (commonly called asphalt, [1] blacktop, or pavement in North America, and tarmac or bitumen macadam in the United Kingdom and the Republic of Ireland) is a composite material commonly used to surface roads, parking lots, airports, and the core of embankment dams. [2]
Asphalt concrete is usually placed on top in a road. Asphalt concrete pavement mixes are typically composed of 5% bitumen (known as asphalt cement in the US) and 95% aggregates (stone, sand, and gravel). Due to its highly viscous nature, bitumen must be heated so it can be mixed with the aggregates at the asphalt mixing facility.
Bitumen (asphalt or coal-tar pitch) is a material made up of organic liquids that are highly sticky, viscous, and waterproof. [1] Systems incorporating bituminous-based substrates are sometimes used to construct roofs , in the form of "roofing felt " or "roll roofing" products.
A more durable road surface (modern mixed asphalt pavement), sometimes referred to in the U.S. as blacktop, was introduced in the 1920s. Instead of laying the stone and sand aggregates on the road and then spraying the top surface with binding material, in the asphalt paving method the aggregates are thoroughly mixed with the binding material ...
The asphalt millings are blended with asphalt emulsion, foamed bitumen, or soft bitumen to rejuvenate the aged asphalt binder. [34] [36] New aggregate may also be added. The resulting asphalt mix is paved and compacted. It may serve as the top pavement layer, or it may be overlaid with new asphalt after curing. [37]
Asphalt plants for road construction Asphalt plant in Belgium The manufacture of coated roadstone demands the combination of a number of aggregates , sand and a filler (such as stone dust), in the correct proportions, heated, and finally coated with a binder, usually bitumen based or, in some cases tar , although tar was removed from BS4987 in ...
The terms bitumen and asphalt are often used interchangeably to describe highly viscous to solid forms of petroleum that have been used in construction since the fifth millennium B.C. Bitumen is distinct from tar, which properly describes a product formed by pyrolysis (destructive distillation) of coal or wood.
Pitch produced from petroleum may be called bitumen or asphalt, while plant-derived pitch, a resin, is known as rosin in its solid form. Tar is sometimes used interchangeably with pitch, but generally refers to a more liquid substance derived from coal production, including coal tar , or from plants, as in pine tar .