Self-healing properties of steel slag asphalt mixture based on experimental characterization and 3D reconstruction

•Steel slag as a microwave absorber can significantly improve the microwave sensitivity of steel slag asphalt mixture.•The self-healing rate of steel slag asphalt mixture can be increased by more than 30% under microwave heating.•The damage and healing state can affect the internal void size, shape, and connectivity characteristics of asphalt mixture.•Fissures and connected voids are proposed to quantitatively evaluate the damage and healing of steel slag asphalt mixture.