Comparative Evaluation of Different Methods for Assessing the Glass Transition Temperature of Bituminous Binders

Glass transition is a second order transition that takes place within a relatively narrow temperature range in amorphous or semi-crystalline materials as they become glassy and brittle. The glass transition temperature (Tg) is the temperature selected to represent this transition and is an important indicator of the low temperature properties of materials. In the case of bituminous binders, no standard protocol is currently available for the determination of Tg, so various techniques have been proposed by researchers. The objective of the work presented in this paper is to compare different methods for the determination of Tg of bituminous binders. A set of selected materials was evaluated by means of a dynamic shear rheometer by imposing various test conditions. Different criteria involving both rheological and volumetric parameters were used to analyze experimental data. Obtained results showed a strong dependency of Tg on the adopted testing parameters and criteria.