Enhanced environmental and self-healing performance of asphalt mixture using steel slag as the substrate of functional coatings

Investigation into the fabrication of steel slag-derived functional aggregates with enhanced environmental safety and self-healing properties remains notably limited. In this research, steel slag was recycled as the substrate of functional coating to achieve both environmental hazard reduction and self-healing enhancement in asphalt mixture. The physicochemical characteristics of functional steel slag were evaluated, while the microwave heating and healing performance of asphalt mixture containing functional steel slag were also determined. The results indicated that the functional coating was formed and adhered to the surface of steel slag by ultrasonic impregnation. The functional coating remarkably reduced environmental hazards caused by leaching of heavy metal ions from steel slag, and improved the microwave healing capacity of steel slag. The healing rate of nano-Fe 3 O 4 slag asphalt mixture reached 79.1 % after 60 s of microwave heating, which is 1.9 times higher than that of ordinary steel slag asphalt mixture. This study demonstrated dual benefits in enhancing the self-healing efficiency of steel slag-reinforced asphalt concrete and mitigating environmental risks associated with heavy metal ion leaching from the steel slag.