Study on the instantaneous healing characteristic of asphalt under cyclic loading

Ravelling damage is a typical road stripping distresses, which is due to the repeated loading of vehicles. However, the instantaneous pressure loads applied to the asphalt mixture also make asphalt re-adhere to the aggregates or close the cracks inside asphalt, and promote pavement healing. Therefore, in laboratory evaluation, the instantaneous pressure in the real pavements should be considered during the fatigue test of asphalt materials. In this study, cyclic tension-healing loading at low stress is applied to the asphalt–aggregate combination samples using the universal testing machine to evaluate the fatigue performance of asphalt. Two different loading modes are set: with and without pressure applied during the healing interval. The response and performance of base asphalt and SBS-modified asphalt are investigated and compared. Two new indices are proposed to evaluate the bearing ability of asphalt materials under repeated loading. It is found that under the same cyclic loading, the bearing durations of SBS-modified asphalt before the yield point and during the failure propagation are both longer than those of base asphalt, showing the superior fatigue behavior and bearing capacity of SBS-modified asphalt. Compared with the loading mode without instantaneous pressure during the healing interval, the samples applied with instantaneous pressure showed better bearing capacity, indicating that the instantaneous pressure during the healing interval has a significant positive effect on prolonging the service life of asphalt materials. Besides, an index of evaluating the instantaneous healing characteristic of asphalt is proposed.