Crack monitoring and self-healing properties of multifunctional asphalt mixture containing steel slag and carbon fiber towards sustainable pavement

Abstract

Steel slag (SS) as alternative aggregate is a sustainable solution to alleviate the shortage of natural aggregate resources. This study aims to systematically assess the feasibility of multifunctional asphalt mixture (MAM) containing SS and carbon fiber (CF) for crack monitoring and self-healing. Firstly, the MAM was prepared by incorporating SS and CF into the asphalt mixture. Then, the conductive, thermal, microwave heating, self-healing, and road properties of the MAM were comprehensively evaluated through a series of laboratory experiments to determine the optimal combination formula of SS and CF. Based on this, the crack of the MAM was monitored by the digital image correlation (DIC) technique and digital acquisition and recording system (DARS) to evaluate the ability of the MAM to sense the damage evolution. Finally, the effect of different healing moments on the healing efficiency of the MAM was investigated. The results show that the incorporation of SS and CF can significantly improve the conductive properties of asphalt mixture, providing the necessary electrical basis for the MAM to achieve the crack monitoring function. The MAM containing SS and CF exhibits excellent microwave heating efficiency and acceptable microwave heating uniformity, which contributes to improving the self-healing properties of asphalt mixture. Based on the multi-index optimization results, a combination formula of 50 % SS replacement and 0.15 wt% CF is recommended that could achieve ideal comprehensive performance. The cracks in MAM can be monitored in real time through the variation of the electrical signals, and efficient healing can be achieved by adopting microwave heating at the microcrack stage (i.e., crack size <400 μm). This study provides a valuable reference for the development of intelligent and long-life sustainable pavements.