Induction Heating and Fatigue-Damage Induction Healing of Steel Fiber–Reinforced Asphalt Mixture

Abstract

As a new noncontact method for heating asphalt pavement, electromagnetic induction heating has great prospects for application in snow melting and heating-induced crack healing. In this research, different lengths (1, 3, 5, and 7 mm) and amounts (2%, 3%, and 4% by volume of asphalt) of steel fibers were added to the asphalt mixture to achieve the induction heating of the asphalt mixture. The induction heating rate of the steel fiber was tested. The induction heating rate, vertical heating and cooling rules, and the surface temperature uniformity of asphalt mixture samples with different fiber lengths and contents were then studied in detail. Finally, the heating-induced fatigue-damage healing characteristics of samples with different fiber lengths and contents were analyzed by conducting fatigue-healing cycles. The results show that as the fiber length increased, the heating rate of the fiber and asphalt mixture gradually increased, but the increment gradually decreased; as the fiber content increased, the induction heating rate significantly increased. During the induction heating process, a significant temperature gradient appeared in the vertical direction of samples, and the temperature gradient became more significant as the heating time extended. During the cooling stage, the temperature gradient gradually decreased, apart from a slight temperature rise at the middle and bottom of the samples. The fiber content and length had different effects on the heating and cooling processes. As the fiber length and content increased, the uniformity of the samples’ surface temperature deteriorated. In addition, fiber clusters on the surface of samples exacerbated the nonuniformity of the surface temperature. When the fiber length was 5 mm and the content was 4%, the healing effect was the best and the fatigue life recovery rate reached 70.77%. With the increase of fatigue-healing cycles, the healing rate of the samples decreased gradually. The healing rate of the sample with 3% fiber content was the slowest as the fatigue-healing cycles increased.