Mesoscale modeling of mechanical deterioration in sulfate-attacked concrete

This study presents a mesoscale mechanical deterioration model to investigate the chemo-mechanical degradation of concrete under sulfate attack. The model introduces sulfate-induced volumetric expansion at the microscopic level and incorporates its macroscopic equivalent expansion strain into a mechanical damage framework. A two-dimensional polygonal random aggregate structure is employed to reflect the heterogeneous microstructure of concrete and simulate damage evolution under sulfate attack. Validation against published experimental data demonstrates the model's accuracy in capturing expansion behavior, cracking patterns, and compressive strength degradation under sulfate exposure. Simulations reveal non-uniform damage initiation at aggregate corners and propagation along aggregate–mortar interfaces, ultimately leading to macrocracking and strength loss. A continuous decline in compressive strength with increasing exposure duration confirms the model's predictive capability. The study underscores the critical role of concrete heterogeneity in influencing ion transport, damage localization, and failure mechanisms. By distinguishing between mortar and aggregate phases, the model reflects tortuosity and dilution effects on ion diffusion and reaction product accumulation. This mesoscale framework offers mechanistic insight into the coupled transport–mechanical processes driving sulfate-induced degradation. Despite simplifications such as the exclusion of the interfacial transition zone and post-cracking transport evolution, the model provides a foundation for future refinements and supports the durability assessment of concrete structures in aggressive environments.