Investigation of induction healing effects on electrically conductive asphalt mastic and asphalt concrete beams through fracture-healing tests

Abstract

The purpose of this study is to evaluate the healing capacity of electroactive asphalt mastic and concrete beam samples with induction heating. The electrically conductive steel wool fibers were mixed with asphalt materials to heat the surrounding binders through induction energy. By introducing Newtonian binder flow in the heated asphalt materials, the microcrack healing performance can be significantly improved with the accelerated process. To investigate the induction healing performance, asphalt mastic and concrete beam samples were prepared by incorporating Type 1 steel wool fibers with an approximate length of 6.5mm. Subsequently, the mastic beams were tested with fracture-healing cycles under the three-point bending test and induction healing process. Meanwhile, the concrete beams were tested with fracture-healing cycles using the modified three-point bending test with an elastic foundation support and healing procedure. Prior to the fracture tests, all samples were conditioned in the freezer for 6h at −20°C to limit the viscoelastic and unrecovered deformation. The samples were loaded until the peak value was obtained for fracture tests. During the healing process, the samples were heated at different temperatures (60°C, 80°C and 100°C) within a short period of time. The result shows that the mastic sample can be fully healed at these three temperatures based on the recovered peak loads from the cyclic test. For the asphalt concrete beams, the test results showed that the healing performance increases with the heating temperatures (60°C, 80°C and 100°C). The temperature distribution in the samples at the end of the healing procedure is also captured. Overall, it was found that the asphalt mixture samples still maintained at least half of the original fracture strength after six fracture-healing cycles. The experimental results indicate that the induction healing techniques have promises in elongating the pavement service life.