Self-healing capacity of asphalt mixtures with steel fiber, steel slag and graphite powder, evaluated with microwave induction and fatigue test

Self-healing in asphalt mixtures can be induced by adding particles that are susceptible to heating by electro-magnetic microwaves. This process allows the closure of microcracks caused by the fatigue phenomenon and can extend the service life of the asphalt pavement. In this article, the self-healing index of asphalt mixtures without and with the addition of steel slag (15% and 65.7%), steel fibers, (0.2% and 0.4%), and graphite powder (15% and 65.7%) was evaluated. The index was determined after subjecting the mixtures to fatigue damage, microwave heating, rest, and fatigue damage again. Results showed that all additions led to mixtures susceptible to microwave heating and with healing capacity. A higher self-healing index was observed when the mixture was produced with slag than with graphite powder. It was found that the use of a higher content of steel fibers was more effective for healing, and for successful healing, the mixtures must be heated to temperatures ranging between 50 degrees C and 75 degrees C. The results also showed that it is possible to achieve high healing values without hav-ing to subject the mixtures to microwave heating.