Numerical investigation of external sulfate attack and its effect on chloride binding and diffusion in concrete

Reinforced concrete (RC) structures may suffer from serious durability problems during long-term service. To investigate the deterioration of RC structures subjected to the dual attacks of chlorides and sulfates, this study proposes a coupled model for external sulfate attack (ESA) and its effect on chloride binding and diffusion. To account for the influence of sulfate attack on chloride binding, a reduction function is proposed. The effect of sulfate-induced damage on the chloride diffusion and chloride binding is considered through a damage function. The coupled model is validated against third-party experimental data from multiple perspectives. Some important factors such as solution concentration, immersion time, curing time and water-cement ratio, as well as how these factors affect the impact of sulfate attack on chloride transport, were elaborated. The findings may bring insights to the durability design of RC structures serving in harsh environments.