Bitumen is soluble in carbon disulphide (CS2). The Indian specifications require that the bitumen should have 99 per cent solubility. Lesser value indicates presence of mineral matter in bitumen and can affect the properties of bitumen.
IS Requirement for Bitumen
Some of the important properties required by IS for the various grades of bitumen are given in Table.
Table: Requirements for different Paving Grades of Bitumen
The properties of bitumen cab be enhanced by the addition of a polymer or crumb rubber or natural rubber. Polymer Modified Bitumen (PMB) is increasingly being used for roads carrying heavy traffic.