Characterization of Fatigue and Healing in Asphalt Binders

Asphalt mixtures have two healing mechanisms: adhesive healing at the asphalt-aggregate interface and cohesive healing within asphalt binders. This study investigates the effects of cohesive healing exclusively, without considering the interaction of aggregates. This study also introduces a methodology of quantifying healing using the dissipated energy approach and the dynamic shear rheometer test with a specifically designed intermittent loading sequence. The ratio of dissipated energy change approach, which is based on the fundamental concept of dissipated energy and has been successfully applied to study hot mix asphalt (HMA) mixture healing, is applied to the binder. By doing so, a healing rate, defined as the rate of dissipated energy recovery per unit of rest time, is used to quantify the healing potential of asphalt binders. The results indicate that binder type, strain level, and temperatures have important impact on healing. It is recommended that the research methods introduced in this study be further applied to asphalt mastics and sand asphalt mixes to study adhesive and cohesive healing in HMA mixtures and provide fatigue-healing information for pavement design.