Healing characteristics of asphalt binder

The healing performance of asphalt binder has a critical impact on the fatigue performance of asphalt binders, mixture and pavement. Although studies of the healing characteristics of asphalt binder can be found in some references, the subject has not been researched thoroughly. No universal healing evaluation index currently exists, and the fatigue and healing processes are not fully understood. For this study, experiments were performed to characterize the healing characteristics of four typical asphalt binders. Healing indices are put forward, and factors that affect healing performance are examined in this paper. Finally, the fatigue and healing processes of asphalt binder are investigated by analyzing test specimen cross-sections. The findings from this study, although based on a limited number of binders, suggests that HI1 (the modulus ratio) and HI2 (the cycle number ratio) are suitable healing indices. Rest periods and microstructural configurations significantly affect the healing performance of asphalt binder. Healing affects the fatigue performance only when the modulus value is greater than the modulus value when rest periods are applied. During fatigue testing, damage starts at the outer edge of the specimen, and then develops towards the middle of the specimen.

► We established two suitable healing evaluation indices for asphalt binder.
► Effects of rest periods and microstructural configurations on asphalt binder were studied.
► Digital microscope was used to monitor binder specimen for the first time.
► We found the fatigue process of asphalt binder.