Effect of fiber reinforcement on self-healing ability of asphalt mixture induced by microwave heating

• Three fibers were used to fabricate asphalt mixtures with self-healing ability. • Microwave healing conditions were determined by one-way ANOVA. • Effect of freeze–thaw cycles on the properties of each mixture was discussed. • The fracture process of each asphalt mixtures was analyzed by DIC technique. • The fiber reinforcement effect of each fiber was discussed by fracture process. Microwave heating is considered to be an effective method for accelerating the healing of the asphalt mixture with cracks that contain microwave-absorbing materials. Three fibers as microwave-absorbing materials (i.e., carbon fiber, steel fiber and steel wool) were used to fabricate self-healing asphalt mixtures, and their mechanical properties and self-healing ability were evaluated by semi-circular bending test. Effect of freeze–thaw cycles on the mechanical properties and healing effect of fiber modified asphalt mixtures were investigated, and the different fiber reinforcing effects were studied by the digital image correlation. Results show that although the addition of fibers can greatly improve the mechanical properties and healing ability of mixtures, freeze–thaw cycles have great adverse effects on these performances. Among the three fibers, steel fiber has the strongest reinforcement effect on the fracture behavior of asphalt mixture, and its reinforcement effect and healing ability are also less affected by moisture and freeze–thaw effect than that of steel wool and carbon fiber. Carbon fiber modified asphalt mixture has the lowest fracture and freeze–thaw resistance. Considering the harmful impacts of freeze–thaw cycles and the beneficial impacts of fiber reinforcing effect, steel fiber is recommended for fabricating self-healing asphalt mixture.