A mechanistic framework for tensile fatigue resistance of asphalt mixtures

Abstract

Fatigue life is one of the most critical factors for asphalt pavement design, which is directly affected by the fracture properties of asphalt mixtures. This study aimed to present a mechanistic framework to determine the Paris’ law parameters A′ and n′ of asphalt mixtures and fatigue life of asphalt pavements. The dynamic modulus test and indirect tensile (IDT) test results were obtained from Texas Data Storage System (DSS) to evaluate the linear viscoelastic properties and fracture properties. Modified Griffith crack criterion in tension was used to determine the damage density rate and pseudo J-integral of macrocracks appeared in the post-peak phase of the IDT test, and the damage density with time was shown as a sigmoidal shape from microcracking initiation. The Paris’ law parameters were then computed using the regression analysis in the macrocracking stage. It was shown that the fracture resistance of asphalt mixtures could be characterized using n′, and a smaller value of n′ indicates a better fracture resistance. The mode-I fatigue life equation for reflection cracking in asphalt pavements was also proposed based on the J-integral from the finite element model and Paris’ law parameters, which shows that the empirical fatigue life transfer function could also be determined from actual material properties and pavement structural boundary conditions.