Numerical simulation study on the mechanical behaviors of frost‐damaged recycled sand powder concrete

Abstract This study established a multiphase, three‐dimensional finite element model of recycled sand powder concrete (RSPC) using the ABAQUS software. A freeze–thaw damage model based on the deterioration of mechanical properties was developed from experimental freeze–thaw test results and applied to the micro‐scale numerical simulation. The results indicated that the mechanical properties of RSPC deteriorate with increasing freeze–thaw cycles, and defects in recycled micro‐powder and recycled fine aggregates become more pronounced during the freeze–thaw process. The numerical simulation results showed a maximum error of 12.97% compared to experimental data (all within 15%), confirming the validity of the model. Specimen failure was primarily concentrated at the bonding interface between aggregates and new/old mortar, with an overall “X‐shaped” failure pattern. Furthermore, as the number of freeze–thaw cycles increased, defects in ITZ2 (the interfacial transition zone between aggregates and old mortar) accelerated the propagation of freeze–thaw damage within the concrete, significantly amplifying internal damage in RSPC.