Asphalt

Introduction and application

Asphalt is a sticky, black and highly viscous liquid or semisolid substance and consists of bitumen and aggregate. The primary use of asphalt is in road construction, where it is used as the glue or binder for the aggregate particles.

Analysis using DSC

DSC is useful in studying the thermal behaviour of asphalts. It gives important parameters such as glass transition temperature, range of melting temperature of crystallites, and enthalpy of melting. Immediately following the Tg transition a small exothermic effect has been seen for most of the asphalts.

This is believed to be the result of crystallization which occurs during the heating process. Following this exothermic effect are two or three endothermic peaks. The third one usually appears as a shoulder on the second peak. DSC testing of fractions based on their different chemical nature indicates that naphthene aromatics make a great contribution to the endothermic effect of the parent asphalt.

Polar aromatics are presumed to be mainly responsible for the shoulder peak since they show a small endothermic effect at about the same temperature range. Asphaltene, due to its chemical nature, shows no endothermic effect.