Multiphase and Mesoscale Numerical Method to Examine the Evolution of Cracked Recycled Aggregate Concrete under Sulfate Attack

Cracks usually exist in recycled aggregate concrete (RAC). In a sulfate environment, a crack can accelerate RAC deterioration and steel corrosion. In this paper, considering the damage zone (DZ) and cracking, a seven-phase model of cracked RAC (CRAC) was developed to investigate the damage evolution of CRAC exposed to sulfate attack. The diffusivity of each component was considered, while the aggregate was assumed to be impermeable. A damage model of CRAC susceptible to sulfate assault was established at the mesoscale, and the proposed model was confirmed by experiments. The impacts of cracking and the DZ were examined. The results show that, the length of the DZ has a more vital impact on the diffusion of sulfate ions than the width of the DZ in CRAC. Furthermore, compared with crack length, we found that crack width has a more significant effect on CRAC degradation. Additionally, rectangular and V-shaped cracks have a similar effect, while curved cracks have a greater impact on sulfate erosion in CRAC due to their irregular shape.