Interfacial Damage Mechanisms and Performance Prediction in Recycled Aggregate Concrete

To address the growing demand for sustainable construction and efficient recycling of waste concrete resources, this study investigates the interfacial performance and mechanical property prediction of recycled aggregate concrete (RAC) under varying recycled aggregate (RA) replacement ratios (r = 0%, 30%, 60%, 100%). A comprehensive experimental program was implemented, including uniaxial compression tests and microscopic characterization using scanning electron microscopy (SEM), to evaluate the macro- and microscale damage evolution and interfacial transition zone (ITZ) properties of RAC. Based on Weibull’s statistical strength theory, a constitutive model for RAC under compression was developed, and a two-dimensional random aggregate model was implemented in Abaqus to simulate the damage initiation and propagation processes at different replacement ratios. The results demonstrate that the compressive strength of RAC decreases as the RA replacement ratio increases, while the optimal interfacial and mechanical performance is achieved at a 30% replacement ratio. The study reveals that failure in RAC initiates at the ITZ between the recycled aggregates and cement matrix, subsequently propagating to complete structural failure. The proposed constitutive model accurately predicts the stress–strain behavior of RAC across different replacement ratios, showing excellent agreement with experimental data. These findings provide valuable insights into the interfacial performance and failure mechanisms of RAC, offering a theoretical foundation for optimizing the design and application of recycled aggregate concrete in sustainable engineering projects.