Prediction of Dynamic Modulus of Hot Mix Asphalts with Reclaimed Asphalt Pavement

Abstract

This study evaluated the viscoelastic properties of a performance grade (PG) binder blended with different percentages of binders recovered from reclaimed asphalt pavement (RAP) for conditions (materials, climate, and specifications) prevailing in Oklahoma. The viscoelastic properties of the blended binders were then used to estimate dynamic modulus (E∗) values of the new mixes with RAP by using the Witczak model through time-temperature superposition (TTS) principles. The recovered binder from RAP was found to be significantly stiffer than the virgin binder (PG 64-22). The addition of RAP increased the complex modulus (G∗) of the base binder, so did the E∗ of the corresponding mix. The creep stiffness resistance of the asphalt binder at low service temperatures decreased with the addition of RAP. With up to 10% RAP binder, no notable changes were observed in the viscosity and PG grade of the virgin binder. With 25% and 40% RAP binder, the PGs of the blended binders were found to be PG 70-16 and PG 76-16, respectively. It was observed that the E∗ master curves predicted from PGs of the blended binders were in close agreement with those estimated from the laboratory-measured E∗ data. The dynamic shear rheometer (DSR) data of rotational thin film oven (RTFO)-aged blended binders predicted significantly lower E∗ values compared to the measured ones. The E∗ values predicted from rotational viscosity (RV) test data were found to be higher than the measured E∗ values. The findings of this study are expected to provide transportation professionals with a better understanding of new mixes with high RAPs.