The present research studies the properties that predict the susceptibility of aggregates for bituminous mixtures to microwave heating. In particular, the relationship between the dielectric properties of the rock and its susceptibility to microwave radiation.

Several laboratory tests on 26 aggregates from different sources (igneous, metamorphic, and sedimentary) have been carried out. The targets were to determine the susceptibility to microwaves as measured by the direct heating parameter T70 (the time needed by the aggregate to reach the temperature of 70 °C in standard conditions) and to measure the dielectric constant, the loss factor, and the loss tangent of the rocks by the cavity perturbation method. As a result, a model for the relationship between the T70 parameter and the loss tangent has been proposed. The model contributes to a more in-depth knowledge of the complex phenomenon of aggregate heating with microwaves, which is crucial for developing self-healing asphalt pavements based on the heating treatment with microwaves.