Low-Temperature Fracture Toughness Study for Hot Mix Asphalt and Warm Mix Asphalt Under Pure Mode I and II Loading Condition

A linear elastic fracture mechanics method is proposed to investigate the fracture behavior of hot mix asphalt and warm mix asphalt; this method was used in this study to calculated the fracture toughness of hot mix asphalt and warm mix asphalt containing 3% Sasobit at low temperatures (0, − 10, and – 20 °C) and two types of bitumen (60/70 and 85/100). A semi-circular specimen with an edged crack under three-point bending load mode was used to create different loading modes, including pure mode I and pure mode II, to test the fracture toughness. The critical stress intensity factor was calculated using the critical load obtained from the failure test. The shape factor was determined from finite element analysis. The results show that hot mix asphalt has a higher fracture toughness against crack growth than the warm mix asphalt containing Sasobit. In addition, the fracture toughness of asphalt mixture with a penetration grade of 85/100 against crack growth is more than that of the mixture with a penetration grade of 60/70. The minimum fracture toughness of hot mix asphalt and warm mix asphalt occurred in pure mode I loading condition.