Self-Healing Asphalt Materials Using Microcapsules and Induction Heating: A Review

Road pavements are exposed to heavy traffic and changing weather conditions every day. Over time, small cracks form inside the asphalt material, and if these cracks are not repaired, they grow into larger problems that can cause the road to fail. Traditional repair methods require closing the road, bringing in workers and equipment, and using large amounts of new material. Self-healing asphalt is a new approach in which the road material can repair its own cracks without any human action or with only minimal intervention. Two of the most promising technologies for self-healing asphalt are microcapsule-based healing and induction heating. Microcapsules are tiny particles filled with a healing liquid that is released when a crack passes through the capsule. Induction heating uses an electromagnetic field to generate heat inside the asphalt material, which softens the binder and allows small cracks to close. This paper reviews published journal research on both technologies, covering the design of microcapsules, the mechanisms of healing, the performance results from laboratory and field studies, and the combined use of both methods. The review shows that microcapsule systems can recover 71 to 90 percent of the original tensile strength and close 76 to 93 percent of crack width, while induction heating systems can recover 71 to 92 percent of fatigue life. Combined systems that use both microcapsules and induction heating consistently show higher healing performance than either method used alone. The paper also discusses challenges related to capsule durability during mixing, heating energy efficiency, and long-term field performance, and suggests important directions for future research.