Microwave Deicing of Functional Pavement Using Sintered Magnetically Separated Fly Ash as Microwave-Heating Aggregate

Microwave-deicing technology is a clean and efficient method, but due to the inefficient microwave absorptivity of pavement materials, this technology is difficult to apply in large-scale applications. The microwave absorptivity of pavement materials can be greatly improved by functionalized aggregate, which makes microwave deicing possible. Magnetite, a common microwave-absorbing material, is an outstanding microwave absorber that can be used in pavements for deicing. In this work, magnetite was scattered in functional aggregate as a microwave-deicing functional phase, and the microwave-heating aggregate (MHA) was prepared by means of sintering to realize aggregate functionalization. Microwave-deicing mortars were prepared using MHA. The effect of aggregate content on average heating rate, reflectivity, and the effect of ambient temperature and ice layer thickness on deicing performance were investigated, and the heating uniformity of the mortar specimen is discussed. The results indicate that the average heating rate of MHA ($4.83°\mathrm{C}/\mathrm{s}$) is much higher than that of ordinary aggregate ($0.49°\mathrm{C}/\mathrm{s}$). Thus, the deicing performance of the deicing pavement was greatly improved by adding MHA compared with ordinary pavement; the deicing time of MHA100 at $-20°\mathrm{C}$ and $-5°\mathrm{C}$ decreased by 56.0% and 54.8%, respectively. The deicing performance is greatly influenced by ambient temperature but less influenced by ice-layer thickness. Adding MHA reduced the heating uniformity of mortar specimens, which may degrade the deicing performance.