The common binders used in bituminous road constructions are road tars and Bitumen. Bitumen has gradually replaced road tar for road construction purposes mainly because of its greater availability as compared to road tar. It is principally obtained as a residual product in petroleum refineries after higher fractions like gas, petrol, kerosene, and diesel, etc., are removed generally by distillation from suitable crude oil. Indian standard institutions define Bitumen as a black or dark brown non-crystalline soil or viscous material having adhesive properties derived from petroleum crude either by natural or by refinery processes.
