Exploring master curve parameters to distinguish between mixture variables

Abstract

It is well known that mixture variables such as binder grade, aging state, recycled binder ratio, and recycling agent type and dose alter the rheological properties of asphalt mixtures. The ability to understand these changes in rheological properties caused by changes in the mixture variables is beneficial to know how to change the mixture variables to impact/improve performance. Rheological evaluation can be employed through linear viscoelastic characterisation in the form of dynamic modulus and phase angle master-curves. This study investigated the ability of dynamic modulus and phase angle master-curve parameters to capture the changes in mixture properties by performing a comprehensive statistical analysis of 74 mixture variable combinations. Evaluated parameters included the mixture Glover-Rowe parameter, inflection point frequency (–β/γ), difference between the glassy modulus and the inflection point modulus (γ), –β/γ versus γ, and the lower and upper asymptotes of the sigmoidal master-curve. The effect of changes in mixture variables on master-curve parameters are qualitatively compared to expected mixture field cracking performance as well. Aging and low- and high-temperature performance grades exhibited a strong negative correlation to mixture G-Rm and –β/γ parameters whereas a strong positive relationship was exhibited to the γ parameter indicating the negative impact of increase in these parameters on cracking performance.