Investigation of the Macroscale and Mesoscale Fracture Behaviors of Concrete Based on a Phase Field Regularized Cohesive Zone Model

Cracking has always been a critical problem for concrete pavement, which would result in performance degradation and even structural failure. Conventional theoretical models and methods, such as the cohesive zone model and extended finite element method, have been widely employed for concrete cracking simulation. However, these approaches still suffer from mesh dependency and numerical complexity. To address these issues, this paper introduced a phase field regularized cohesive zone model (PF-CZM) to simulate the macroscale and mesoscale fracture behavior of concrete. This model was numerically implemented by the finite element method and validated through a traditional example. The sensitivity of calculations to mesh and internal length scale parameter b was discussed. Subsequently, typical Mode I and mixed-mode fracture tests were simulated to investigate the feasibility of PF-CZM in modeling quasibrittle fracture of concrete. The results indicated that simulated crack width was determined by internal length scale parameter b, but the other calculated results of PF-CZM exhibited high independence from element type, mesh size h, and internal length scale parameter b when b/h≥5. Further, the simulation results of PF-CZM were consistent with experimental data, which proved the applicability and effectiveness of PF-CZM in modeling the fracture behavior of concrete at the multiscale. Based on these calculations, the mesoscopic process of damage and crack evolution in concrete were demonstrated. It was also observed that interfacial transition zones were the primary region where cracking and damage were induced due to their inadequate tensile strength and fracture energy. Additionally, different shapes and sizes of aggregates in the crack propagation region led to various deflections during crack propagation and eventually resulted in the presence of diverse crack paths.