Modeling Mode I Cracking Failure in Asphalt Binder by Using Nonconserved Phase-Field Model

Cracking failure in asphalt binder in winter has always been one of the most serious problems in pavement structures. Classical fracture mechanics is the most widely used method to analyze the initiation and propagation of cracks. In this paper, a new modeling and computational toolnamely, the phase-field methodis proposed for modeling the Mode I cracking failure in asphalt binder. This method describes the microstructure using a phase-field variable that assumes 1 in the intact solid and -1 in the crack region. The fracture toughness is modeled as the surface energy stored in the diffuse interface between the intact solid and crack void. To account for the growth of cracks, a nonconserved Allen-Cahn equation is adopted to evolve the phase-field variable. The energy-based formulation of the phase-field method handles the competition between the growth of surface energy and release of elastic energy in a natural way: the crack propagation is a result of the energy minimization in the direction of the steepest descent. Both the linear elasticity and phase-field equation are solved in a unified finite-element framework, which is implemented in commercial software. The Mode I crack simulation is performed for validation. It was discovered that the onset of crack propagation agrees very well with the Griffith criterion and experimental results.