Asphalt concrete resistance against fracture at low temperatures under different modes of loading

•Fracture tests were performed on asphalt concretes at subzero temperature.•Mode of loading affected the crack growth resistance of asphalt concretes significantly.•Coarser aggregates and softer binders improved low temperature fracture resistance of asphalt concretes.•Higher air void contents reduced mixed mode fracture resistance of tested samples.

Asphalt concrete components including binder, aggregate and air void play important roles in the fracture mechanism of asphalt pavements in cold regions. In this research, effects of different binders, aggregate gradations and air void contents on the fracture behavior of asphalt concretes were studied by performing three-point bend tests at − 10 °C using an improved semi-circular bend (SCB) specimen under pure mode I, pure mode II and mixed mode I/II loading. Results showed that as the binder in the asphalt concrete softens, the resistance of asphalt concrete against fracture increases. Coarser aggregates lead to higher fracture resistance, and the mixture containing the finest aggregates was found to resist poorly against fracture under pure shear loading. Meanwhile, it was found that as the air void content increases, the fracture resistance of asphalt concrete at low temperature decreases. Moreover, all the studied asphalt concretes were significantly sensitive to the loading modes, and by increasing shear load, the fracture resistance first decreased and then increased.