Mechanical behaviour of asphalt binders at high temperatures and specification for rutting

This is a study of the temperature dependence of the mechanical behaviour of asphalt binders. Creep-recovery and steady-shear experiments were conducted on selected modified and unmodified binders at 60, 70 and 80 °C, and the results were used to characterise the binders using a nonlinear viscoelastic model. Experimental and model parameters obtained in this manner were all found to follow Arrhenius relationship with temperature. Rutting parameters such as zero shear viscosity, non-recoverable creep compliance, Superpave criterion |G*|/sin δ and apparent viscosity were predicted using the model, and were also found to follow an Arrhenius relationship with temperature. However, it was found that the temperature sensitivity of the binders can vary considerably. Issues with ‘failure temperature’-based grading systems, such as the Superpave high temperature specification, were analysed in the light of the Arrhenius-like temperature dependence and varying temperature sensitivities. Possible ways to consider varying temperature sensitivities in the high temperature specification are proposed.