Fatigue and Healing Characteristics of RAP Binder Blends

Abstract

Reclaimed asphalt pavement (RAP) mixes generally have good moisture and rutting resistance. However, the fatigue performance of the RAP mixes is a matter of concern because the RAP binder is generally brittle because of age hardening. Asphalt mixes can heal and recover from the fatigue damage caused by repeated wheel load application. The healing characteristics of the mix depend to some extent on the flow characteristics as well as the chemical makeup of the binders. Linear amplitude sweep (LAS) testing was performed for evaluating the fatigue performance of RAP binders. The fatigue and healing characteristics of different virgin-RAP binder blends were measured in an oscillation fatigue test conducted with varying rest periods using dynamic shear rheometer. The slopes of the fatigue life versus rest period plots were taken as indicators of the effect of rest period on fatigue life or healing indices (HI). Different rheological and chemical parameters measured in terms of surface free energy and the indices calculated using Fourier transform infrared (FTIR) spectroscopy correlated well with the healing potential of RAP binders.