<scp>Three‐dimensional</scp> meso‐scale finite element modeling of recycled aggregate concrete using cohesive zone method

Abstract The presence of adhered mortar (AM) in recycled aggregates (RAs) significantly affects the mechanical performance of recycled aggregate concrete (RAC). Meso‐scale modeling provides valuable insights into complex phase interactions, enabling a better understanding of RAC behavior. To better understand the effects of AM and interfacial transition zones (ITZs), this study presents a 3D meso‐scale finite element model of RAC with varying RA types, despite the inherent modeling complexities and computational challenges. The proposed model incorporates five phases: virgin aggregates, AM, new mortar, old ITZ, and new ITZ. The ITZs were simulated using the cohesive zone method, while the new mortar and AM were modeled using the concrete damage plasticity model. A customized placement algorithm was implemented in Python for the generation of RAC models. The numerical results were validated against experimental data of four RAC mixes. Parametric studies were conducted to evaluate the effects of AM and ITZ properties on the mechanical behavior of RAC. The results showed a significant influence of AM and ITZ properties. Importantly, the compressive strength of RAC became less sensitive to AM properties as the AM volume fraction in RA decreased. This study provides valuable insights and guidance for future research in realistic 3D meso‐scale modeling of RAC.