δ₂₅ Crack opening displacement parameter in cohesive zone models: Experiments and simulations in asphalt concrete

Recent work with fracture characterization of asphalt concrete has shown that a cohesive zone model (CZM) provides insight into the fracture process of the materials. However, a current approach to estimate fracture energy, i.e., in terms of area of force versus crack mouth opening displacement (CMOD), for asphalt concrete overpredicts its magnitude. Therefore, the δ₂₅ parameter, which was inspired by the δ₂₅5 concept of Schwalbe and co-workers, is proposed as an operational definition of a crack tip opening displacement (CTOD). The δ₂₅25 measurement is incorporated into an experimental study of validation of its usefulness with asphalt concrete, and is utilized to estimate fracture energy. The work presented herein validates the δ₂₅25 parameter for asphalt concrete, describes the experimental techniques for utilizing the δ₂₅25 parameter, and presents three-dimensional (3D) CZM simulations with a specially tailored cohesive relation. The integration of the δ₂₅25 parameter and new cohesive model has provided further insight into the fracture process of asphalt concrete with relatively good agreement between experimental results and numerical simulations.