Iron-based particles for the magnetically-triggered crack healing of bituminous materials

Bituminous road pavements may suffer from cracking over the years due to repeated stresses. In this study, we compare the effect of different sizes and chemical compositions of magnetically-responsive iron-based particles used as additives to heat up road pavements and thus to close cracks. By applying an alternating magnetic field (AMF), we found that there is an optimal size depending on the particle electrical conductivity at which the temperature on the surface of asphalt samples is the highest. Even when particles are well-distributed after mixing, we found that asphalt samples containing larger particles display inhomogeneous heating during the exposure to the AMF. The mechanical recovery of samples during a double torsion test before and after the exposure to the AMF confirmed the healing capability of asphalt materials containing iron-based particles. Based on these results we provide guidelines for the design of magnetically-responsive asphalts for road pavements of enhanced durability.