Pseudo energy-based crack initiation criterion for asphalt-filler composite system under a fatigue shear load

Fatigue crack initiation is the precondition of fatigue crack propagation and failure of asphalt materials. To trace the fatigue crack initiation of asphalt-filler composite system (AFCS) under a fatigue shear load, a pseudo energy-based crack initiation criterion is established by Griffith’ theory and validated by surface energy tests and molecular dynamics simulation in this study. Nondestructive and destructive dynamic shear rheometer tests are performed on the AFCSs with two different volumetric contents of limestone filler (10% and 27%) at different temperatures (15 °C, 20 °C and 25 °C) and one frequency (10 Hz). Surface energy tests of the asphalt binder and molecular dynamics simulations of interface debonding between the asphalt binder and limestone mineral at 15 °C, 20 °C and 25 °C are carried out. Results show that the pseudo energy-based crack initiation criterion of the AFCS can be modeled by dissipated pseudo strain energy, recoverable pseudo strain energy, initial crack size and total surface energy of the material. The interface debonding process between the asphalt binder and filler involves a large proportion of cohesive debonding (68.093%, 71.733%, 84.288% at 15 °C, 20 °C, 25 °C, respectively), and the proportion increases with temperature. The total surface energies of AFCS predicted by the pseudo energy-based crack initiation criterion match with that obtained from the surface energy testing results and the molecular dynamics simulations.