Identification of rheological parameters of modified binders to predict rutting behavior of bituminous concrete mixes

Abstract

Numbers of researchers used binder parameters such as complex modulus (G*) and phase angle (б) in terms of G*/sin (б), Zero Shear Viscosity (ZSV) and non-recoverable creep compliance (J sub nr) at two stress levels to describe the rutting potential of binders. Previous studies have shown that Zero Shear Viscosity and non-recoverable creep compliance obtained from Multiple Stress Creep and Recovery Test (MSCRT) have better correlation with rutting in bituminous mixes compared to G*/sin (б) especially for modified binders. In India, recent guidelines on modified binders have introduced G*/sin (б) as a mandatory test to address rutting performance of modified binders at high temperature. However there is not enough experience gained on binder parameters that would better explain rutting behavior of bituminous mix. Keeping this in view, an attempt has been made to identify most appropriate rutting parameter of modified binders that explains rutting potential of bituminous mix prepared with modified binders. Dynamic Shear Rheometer (DSR) was used to evaluate the different rheological properties of short term aged binders. Wheel tracker, indigenously developed IITKGP rut tester, was used to evaluate the rutting performance of mixes. Correlations were developed between rheological parameters and mix rutting to identify appropriate binder parameter to explain rutting observed in the mix. The results indicate that the non-recoverable creep compliance (J sub nr) obtained from MSCRT appears to have better correlation with rutting resistance of mixes.