Chemical degradation vs. creep loading vs. hydration processes in cement-based materials immerged in seawater characterized with a multiscale model

Abstract Upon contact with seawater, concrete undergoes degradation caused by the diffusion of aggressive ions into its porous network and their reaction with cement hydration products. In addition, time-dependent deformations occur resulting from long-term operational use and mechanical loading. The analysis of these coupled chemomechanical phenomena is complex and requires the development of innovative approaches. A micromechanical model has been developed to analyze these phenomena at the microscopic scale. A multiscale approach has been performed for the evaluation of their effects in mortars. Creep loading has opposite effects compared to chemical degradation due to seawater ingress and the evolution of cement hydration at early ages. After 3 days of loading, the model can reproduce the experimental measurements as the chemical reactions occur slowly, but differences are larger during the first 3 days. The contradictory effects of the formed phases balance each other out, resulting in similar creep behavior in tap water and seawater. This indicates that to limit the failure risk of offshore concrete structures it is necessary to reduce the loading at the early stages during the first days of seawater attack.