Investigation of fracture performance of asphalt mixtures considering size effect law and equivalent crack propagation law

The integration of the Size Effect Law (SEL) and the equivalent Linear Elastic Fracture Mechanics (LEFM) in characterizing the fracture behavior of asphalt mixtures has received limited attention. This study presents a preliminary exploration into the application of equivalent LEFM on the fracture characteristics of two asphalt mixtures, AC10 and AC16, accounting for variations in specimen size. Semi-circular Bending (SCB) tests were conducted on specimens with four different diameters (D = 76 mm, 100 mm, 125 mm, and 150 mm) and three notch-to-radius ratios (α = 0.2, 0.4, and 0.6) at a temperature of −10 °C. The equivalent crack propagation (ECP) length, crack growth resistance, and the size of the Fracture Process Zone (FPZ) were determined and subjected to analysis. The findings revealed a size effect on the ECP length, crack growth resistance, and FPZ size, with an increase in specimen size leading to a corresponding increase in these parameters. Conversely, an increase in α resulted in a decrease in all three types of data. A power law relationship was established between the ECP length and crack growth resistance. It was observed that AC16 demonstrated superior fracture resistance compared to AC10, particularly in terms of crack growth resistance. The initial notch length, ECP length, and FPZ size were found to be of the same order of magnitude, suggesting that the equivalent LEFM can produce more accurate fracture results under low temperatures than the traditional LEFM.