Self-healing efficiency of ferrite-filled asphalt mixture after microwave irradiation

Asphalt-based composites have the ability to heal themselves. Under certain conditions, strength and stiffness modulus can be restored so that the fatigue life can be extended. However, without the aid of external influences (energy supply or material supplement), the self-healing ability of asphalt mixture is quite limited. In this paper, the efficiency of self-healing of asphalt mixture with Ni-Zn ferrite powders was analyzed based on the concept of microwave heating. The recovery rate of stiffness modulus and the fatigue life extension ratio were adopted to evaluate the self-healing efficiency of asphalt mixture. Different influence factors, such as heating temperature, healing time and damage level, were analyzed in this study. The analysis results proved that Ni-Zn ferrite powders can promote the self-healing ability of asphalt mixture significantly. It is found that when the asphalt mixture is filled with 80% ferrite powders (volume fraction of mineral powders), under the condition of healing for 3 h after heating to 55 °C by microwave, the fatigue life extension ratio of 50% damaged ferrite-filled asphalt mixture can reach 1.33.