In this paper, steel slag/steel fiber composite asphalt mixture were prepared. The effects of the addition of steel slag and/or steel fibers on the mechanical, thermal, induction heating and healing properties of asphalt mixture were investigated. The results showed that adding steel slag and/or steel fibers improves the water stability, particle loss resistance and fracture energy of asphalt mixtures. The addition of steel fibers increased the thermal conductivity and thermal diffusion of the asphalt mixture, and steel slag showed a reverse effect. Steel slag asphalt mixture cooled more slowly than steel fiber asphalt mixture, which is beneficial to crack healing of asphalt mixture. The composite of steel fibers and steel slag can enhance the induction heating speed, heating homogeneity and thus enhance the induction healing ratio of asphalt mixture. It is concluded that steel slag/steel fibers composite asphalt mixture achieves good mechanical and induction healing properties.

In this paper, the flow behaviors of asphalt binders were investigated through DSR viscosity-frequency sweep test to find out their potential optimal self-healing temperatures and the real self-healing ratios of the binders at different temperatures were measured through fatigue-healing-fatigue test to confirm the optimal self-healing temperatures. The healing time of asphalt binders needed for full healing was studied as well. It is found that both fresh and aged Pen bitumen binders show near-Newtonian fluid state at their softening point temperatures, at which asphalt binders showed optimal self-healing properties to heal fatigue damage. It is also found that ageing of the binder increases its optimal self-healing temperature. It means that the optimal temperatures of asphalt binders are associated to the bitumen type and ageing. Finally, the Wool and O's Connor model can be used to determine the healing time needed by asphalt binder to achieve full healing, where the accumulated dissipated energy recovery is recommend as a suitable healing index.