Impact of microwave-induced heating on the self-healing performance of recycled hot-mix asphalt (HMA) under multiple damage cycles

This research explored the microwave-induced heating on the self-healing performance of recycled mixes under multiple damage cycles. Microwave-induced treatments with various heating durations ranging from 0 to 6 min were applied to heal the damaged mixes. The study found that the treatment of microwave-induced heating significantly enhances the self-healing performance of mixtures. When the microwave heating duration exceeds 4 min, recycled mixtures with lower ageing degrees or longer blending times achieve self-healing effects comparable to those of conventional virgin mixtures. Besides, a longer blending time led to a higher degree of blending and resulted in a thinner reclaimed binder layer and a thicker blended binder layer, which in turn facilitated better self-healing capabilities of recycled mixtures. However, with the use of more severely aged reclaimed materials, the fracture energy and self-healing rate of that group were significantly lower. In addition, a self-healing model of recycled mixes has also been proposed to analyse this phenomenon.