Abstract:
The selection and specification of asphalt binder is one of the factors that ultimately affect the long-term performance of asphalt pavements. Many agencies currently follow AASHTO M320 for their binder specifications, where the ratio of dynamic modulus to the sine of the phase angle, |G*|/sind, is the binder rutting parameter. However, an alternative now exists, AASHTO M332, which uses the non-recovered creep compliance, Jnr , for this purpose. In this paper, the relative merits of these two parameters are compared using experimental results from 21 different asphalt mixtures from Arizona. The rutting parameters according to AASHTO M332 and M320 were determined for each of the binders in these mixtures and, for each mixture, two rutting performance tests were conducted: Hamburg wheel tracking test and repeated load permanent deformation test. The two binder rutting parameters demonstrated very high correlation to one another for non-polymer modified asphalts, but inconsistent correlation for polymer modified asphalts. Both Hamburg wheel tracking tests and repeated load permanent deformation tests showed positive correlations to both |G*|/sind and Jnr. It was concluded that, while both parameters showed good correlation, the Jnr of the binder relates better to mixture rutting than does |G*|/sind. Considering the results in this study, it is believed that Jnr is a slightly better rutting parameter for binder specifications.
