Evaluation of self-healing of asphalt concrete through induction heating and metallic fibers

While healing through induction heating is promising, the effectiveness of this technology is yet to be demonstrated as limited studies have been conducted to study the recovery of cracking damage and fracture resistance properties after healing. The objective of this study was to test the hypothesis that a new generation of asphaltic materials could be artificially healed while in-service by embedding metallic fibers in the mix and by applying a magnetic field at the surface. To achieve this objective, an open-graded friction course (OGFC) was successfully designed and prepared to incorporate up to 5% steel and aluminum fibers by weight of the mix. Based on the results of the study, it was found that the control mix and the mix prepared with aluminum fibers exhibited greater ultimate load at failure prior to healing than the specimens with steel fibers. Yet, differences were not statistically significant. The induction heating experiment was conducted successfully and showed the feasibility of inducing Eddy currents in the metallic fibers without contact to the specimens. After healing, the control mix had the highest ultimate load after healing although it was not successfully heated through Eddy currents; yet, differences were not statistically significant. This indicates that other healing mechanisms were present that allowed the control specimens to heal during the recovery period. Healing efficiency was the highest for the control specimen as it approached 85%. Healing efficiency for the specimen with aluminum and steel fibers was 72 and 62%, respectively. Microscopic image analysis demonstrated that induced cracks healed efficiently during the recovery period.