Asphalt is a residue of the process of natural distillation of petroleum or the distillation of crude oil in a petroleum refinery, it is also known as bitumen. It is a black, sticky and highly viscous liquid; it is also available in semi-solid form. The naturally occurring bitumen is known as crude bitumen while the bitumen formed in petroleum refineries is known as refined bitumen.
A major portion of the asphalt produced is widely used in the construction of roads, highways, playgrounds etc., it is also used in water proofing of roofs .
The characteristics of asphalt/bitumen are –
- They have good adhesive properties and can combine materials together without changing their physical or chemical properties.
- They are insoluble in water and form a very good sealant for waterproofing.
- Asphalt and bitumen have very good thermoplastic properties, they are liquid when heated and solidify when cooled.
- Asbestos and Bitumen are highly durable .They can last for years if proper care is taken.
- In road construction bitumen and asphalt are effective in load distribution of traffic to the layers beneath.
It is a very economical material and is extensively used throughout the world.