Asphalt

From Wikinfo

Asphalt is a highly viscous liquid that occurs naturally in most crude petroleums. Asphalt can be separated from the other components in crude oil (such as naphtha, gasoline and diesel) by the process of fractional distillation. A better separation can be achieved by further processing of the heavier fractions of the crude oil in a De-Asphalting Unit which uses either propane or butane in a supercritical phase to dissolve the more aromatic moelecules whichc are then separated.

Further processing is possible by "blowing" the product: namely reacting it with oxygen. Thsi makes the product harder (and more viscous) where the end use requires it.

It is sometimes confused with tar, which is an artificial material produced by the destructive distillation of organic matter. Both tars and asphalts are classified as bitumens, a classification that includes all materials entirely soluble in carbon disulphide.

Asphalt is commonly used in roofing shingles, and combined with mineral aggregate to make Asphalt concrete for making roads etc. The Asphalt used for Asphalt concrete is called Bitumen in many countries and is blended up from various components in an oil refinery to meet the desired hardness.

Asphalt is commonly mis-spelled and mis-pronounced Ashphalt.

Asphalt is rather hard to transport in bulk (it goes hard unless kept very hot) so it is sometimes mixed with diesel or kerosene before shipping: then at the other end these lighter materials are sepaarted out again. This mixture is often called Bitumen Feedstock, or BFS.

Bitumen was formerly used in mummification.