Recycling of steel slag in sustainable bituminous mixtures: Self-healing performance, mechanism, environmental and economic analyses

The accumulation and disposal of steel slag (SS) is a growing problem with economic impact and environmental burden. This work aims to use SS to partially replace limestone to prepare sustainable self-healing steel slag bituminous mixtures (SSBM) to reduce maintenance costs and reduce greenhouse gas emissions. The damage-healing test, the microwave heating test of SSBM was carried out, and CT scanning was performed on SSBM before and after damage-healing. Cost-benefit analysis (CBA) was performed on the SSBM. The self-healing performance of SSBM is far better than traditional mixtures. The scale evolution of voids is the essential reason for the increase of fracture resistance of SSBM after healing. In the pre-crack (void) stage, the self-healing theory was improved based on the morphological repair theory of void interface. CBA results show that SSBM is economically and ecologically efficient. This work is helpful to the reuse of SS and the development of sustainable pavement.