Materials used in road pavements

Other than soil, the materials most used in road pavements are bitumen, cement, lime, rock, gravel and recycled material aggregates. Each is discussed here.

Bitumens are viscous liquid or semi-solid materials, consisting essentially of hydrocarbons and their derivatives, which are soluble in trichloroethylene (BSI, 2009a). While bitumens occur naturally (e.g. in lake asphalts containing mineral materials), the vast majority are the penetration-grade products of the fractional distillation of petroleum at refineries. Bitumens that are produced artificially from petroleum crudes (usually naphthenic- and asphaltic-base crudes) are known as refinery bitumens.

The term ‘asphalt’ is used in the US technical literature to describe what is termed ‘bitumen’ in the UK and Europe. Following agreement by the European Committee for Standardization (Comité Européen de Normalisation, CEN), in Europe the term ‘asphalt’ is reserved for materials containing a mixture of bitumen and mineral matter (e.g. lake asphalt or hot rolled asphalt).