Asphalt is a dark brown complex mixture, which consists of hydrocarbons with different molecular weights and their nonmetallic derivatives. It is an organic liquid with high viscosity, mostly in the form of liquid or semi-solid petroleum, with a black surface and soluble in carbon disulfide and carbon tetrachloride.
Asphalt is a waterproof, moisture-proof and anticorrosive organic cementing material. Asphalt is mainly divided into three types: coal tar asphalt, petroleum asphalt and natural asphalt. Among them, coal tar pitch is a by-product of coking.
Petroleum asphalt is the residue after crude oil distillation. Natural asphalt is stored underground, and some of it forms ore beds or accumulates on the surface of the earth's crust. Asphalt is mainly used in paint, plastic, rubber and other industries, and also used for paving roads.