Utilization of steel slag as aggregate in asphalt mixtures for microwave deicing

Under the dilemma of non-renewable natural resources shortage and environmental pollution issues, as a novel aggregate used in asphalt pavement, the application of steel slag is propitious to the improvement of the environment and the enhancement of economics. Meanwhile, steel slag has great potential for microwave heating as an excellent microwave absorbing material, which can contribute to remove the ice layer on the pavement. The primary objective of this work was to explore the feasibility of the usage of steel slag as the aggregate of asphalt mixtures for microwave deicing, and ascertain the most effective volume and particle sizes for partial replacement of conventional aggregate. The deicing mechanism of microwave heating pavement was firstly introduced. Then, the microwave heating capacity of steel slag with different particle sizes was tested and the surface elements distribution of steel slag was measured. In addition, the XRD test was conducted to analyze the material information of steel slag for its microwave heating capacity. Finally, the surface temperature, thermal conductivity and heating uniformity of asphalt mixture containing different steel slag content were tested. Results show that the particle sizes of 9.5 mm, 2.36 mm and 0.6 mm are considered as the most effective sizes. The thermal conductivity and microwave heating uniformity of asphalt mixtures basically decrease with the increase of steel slag content; while the surface temperature presents a contrary trend. Consequently, the suggested steel slag volume content is 40% and 60%; and the particle sizes of steel slag are selected as 9.5 mm, 2.36 mm and 0.6 mm. The comprehensive evaluation results on the supply sources, environmental hazard and cost of steel slag show great feasibility of its utilization in asphalt mixtures for microwave deicing, which is helpful to alleviate the supply shortage of natural aggregates and improve the safety of road traffic in winter.