Interfacial layers in mineral-bitumen composite and durability of asphalt concrete

The strength and durability of asphalt concrete are directly related to the adhesive properties of the bitumen. The destruction of asphalt concrete occurs at the boundaries of its mineral fractions’ connection, i.e., at the adhesive connection. The object of the study is the adhesion strength of bitumen and granite in asphalt concrete. The research method is based on the thermofluctuation theory of strength. The initial increase in adhesion strength can be explained by the fact that during the thermal degradation of bitumen molecules, other active radicals appear to create adhesion bonds. At the same time, there is a process of thermal degradation not only of bitumen but also of the adhesive bonds formed. It is confirmed that the destruction of asphalt concrete occurs at the boundaries of the connection of its mineral fractions, i.e., at the adhesive bond. The character of fracture can be cohesive, but the strength of bitumen at the boundary with the surface of mineral fractions and in the free state significantly differs. Thus, we can conclude that choosing the correct temperature-time technological regime can significantly increase the initial adhesive strength of the formed asphalt concrete. According to calculations, this will also provide an increase in its durability.