A Chemical Transport-Damage Model for Concrete under Sulfate Attack

Based on the constitutive relationships of materials, this study investigates the two-stage degradation of cement-based materials under sulfate attack and proposes a comprehensive chemico-transport model to analyze the volumetric changes, porosity evolution, and crack development during the erosion process. The research reveals that, in the early stage of sulfate attack, the formation of gypsum and ettringite fills the pores, enhancing the concrete's density and slowing the diffusion of sulfate ions. However, over time, the expansive stresses generated by these products lead to structural damage, promoting the initiation and propagation of cracks. This, in turn, accelerates the penetration of the aggressive sulfate solution into the concrete, intensifying the consumption of internal components. Quantitative analysis of sulfate ion diffusion patterns enables the estimation of gypsum formation and the associated consumption of CA, which is crucial for a deeper understanding of the degradation mechanisms of concrete structures in sulfate environments.