Microwave deicing for asphalt mixture containing steel wool fibers

Driving safety deteriorated dramatically on ice-covered road pavement in winter. However, it is a challenge to remove thick ice layer from the pavement surface with conventional technologies. In this study, the microwave heating performance of asphalt mixtures containing steel wool fibers was tested. Firstly, the mechanism of pavement deicing using microwave was introduced. The effect of steel wool fiber on air void content of asphalt mixture is studied, and the fiber distribution is observed. The microwave heating performance of specimens with different types and contents of steel wool were tested under the temperature of −5 °C and −10 °C. The ice-thawing time was measured and the effect of initial temperature and ice thickness on the thawing time was evaluated. Finally, the heating uniformity and sustainability aspects of this technique were assessed. Results show that the optimal steel wool fiber contents for microwave heating of asphalt mixture are 0.3% of 000#, 0.6% of 0# and 0.9%% of 2#, respectively. The ice-thawing time of the pavement with an initial temperature of −10 °C is 9.3% (000#), 11.3% (0#) and 14.8% (2#) higher than that of −5 °C. In addition, every 1 cm increase in ice layer thickness requires 5.9% (000#), 7.7% (0#) and 13.0% (2#) increase in thawing time. A larger diameter of the steel wool helps to improve the heating uniformity. At last, the microwave heating capacity of specimens containing steel wool will not be significantly reduced by the repeated service in the first five winters.