Evaluation of Microdamage, Healing, and Heat Dissipation of Asphalt Mixtures, Using a Dynamic Mechanical Analyzer

Abstract

Microdamage accumulation due to fatigue loading, healing due to rest periods, and hysteresis heating during fatigue testing of asphalt mixtures using a dynamic mechanical analyzer were investigated. Specially fabricated sand-asphalt specimens were tested under a repetitive, controlledstrain torsional mode at 25°C and 10 Hz. Fatigue performance was evaluated using hysteresis loops of stress-pseudostrain and a simple parameter, pseudostiffness, based on the elastic-viscoelastic correspondence principle. Heat generation and dissipation during fatigue testing were also investigated by measuring temperature changes of a tiny thermocouple inside the asphalt mixtures. The results demonstrate that microdamage healing due to rest periods results in an increase of fatigue life. It was observed that the effects of hysteresis heating on the changes of stiffness during the fatigue test were not significant. Successful development of this testing method is suggested as a potential specification-type test method because of its rapidity, repeatability, and accuracy.