Top-down cracking self-healing of asphalt pavements with steel filler from industrial waste applying microwaves

This work shows the self-healing results of surface cracks on bituminous mixtures after microwave heating. Different mixtures (semi-dense AC, BBTM and PA) with diverse types, sizes and proportions of metallic additions were tested (steel wool, steel filing and metallic powder). 3 aspects were evaluated: a) influence of the mass and type of addition on the heating speed; b) temperature increase ratio with the specific energy; c) monitoring of the healing process using ultrasounds. It was found that metallic filler replacing the mineral powder was the most efficient and practical addition. This method allows complete closure of the cracks, using an industrial waste, and offers certain improvements compared to induction heating. The results validate the microwaves healing capacity, as well as the use of ultrasounds for tracking the crack depth.