Understanding the degradation mechanisms of cement-based systems in combined chloride-sulfate attack

Chemical aggressions from the environment, such as salt ions, can damage reinforced concrete structures before they reach their service life. These deterioration mechanisms are coupled. The current research on cementitious material's durability has thus gradually shifted to the field of durability damage caused by the combined action of multiple factors. The research in this study concerns the case of combined chloride-sulfate attacks to provide a better understanding of the coupling phenomena by studying the mutual effect of the chloride and sulfate ions on the materials. The effect of the type of cement and curing duration on the chloride-sulfate attack is also inves-tigated. Experimental results based on different investigation techniques (ICP, XRD, NMR, etc.) clearly show the competition between chloride and sulfate ions, and how the physico-chemical involved mechanisms completely change with respect to the cases of an exposure to a single type of ion.

Automated summary

Chemical aggressions from the environment, such as salt ions, can cause damage to reinforced concrete structures before their expected service life. Research on cementitious material's durability has shifted to studying the combined effects of multiple factors on durability damage. This study focuses on the combined chloride-sulfate attacks, investigating the mutual effect of chloride and sulfate ions on materials and the influence of cement type and curing duration. Experimental results reveal the competition between chloride and sulfate ions and how the involved mechanisms change compared to exposure to a single ion.