Utilization of Solid Waste Steel Slag in Preventive Maintenance Overlays of Asphalt Pavement

Steel slag, a typical industrial by-product in steel-making process, accounts for more than 15% of steel output. The annual output of steel slag in China is about 100 million tons, and accumulated stockpiles have exceeded 1 billion tons. Road engineering is the main available method to recycle steel slag in large quantity. Steel slag has the characteristics of high hardness and wear resistance, which makes it an ideal aggregate for preventive maintenance overlays of asphalt pavement. In this study, steel slag was used as aggregate in preventive maintenance overlays instead of natural aggregate. The results show that micromorphology, adhesion performance and geometric properties of steel slag are significantly better than natural aggregate and positive texture of preventive maintenance overlays increased due to the addition of steel slag. In addition, the displacement results demonstrated that samples containing slag has superior displacement resistance because of stronger interlocking structure.