Asphaltic bitumen is dark brown to black, semi-solid, solid substances consisting essentially of hydrocarbons. They are colloidal systems the disperse phase being the high molecular weight, nonvolatile components and the continuous phase comprising those of low molecular weight.
Asphaltic bitumen are either found in natural or produced from petroleum but as the native products have probably been formed over long periods of time by evaporation of the more volatile components there is no substantial differences between the natural and the manufactured products:
There are main varieties of asphaltic bitumen
Steam refined asphaltic bitumen
Blown asphaltic bitumen
Pitch type asphaltic bitumen