asphslt

Asphalt (en-us-asphalt.ogg 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.[1] It is most commonly modelled 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).[citation needed] One writer states that although a "considerable amount of work has been done on the composition of asphalt, it is exceedingly difficult to separate individual hydrocarbon in pure form",[2] and "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".[3]

In U.S. and Polish terminology, asphalt (or asphalt cement) is the carefully refined residue from the distillation process of selected crude oils. Outside these countries, the product is often called bitumen.

The primary use of asphalt is in road construction, where it is used as the glue or binder for the aggregate particles. The road surfacing material is usually called 'asphaltic concrete', AC in North America, or 'asphalt' elsewhere. Within North America the apparent interchangeability of the words asphalt and 'bitumen' causes confusion outside the road construction industry despite quite clear definitions within industry circles.