An electrochemical model to characterize the chloride ion ingress in multi-phase concrete with the effect of ionic solution

The chloride (C1-) ion ingress is one of the primary causes for concrete structure deterioration. Herein, an electrochemical model is developed to simulate the C1- ion corrosion in a concrete structure with the effect of the surrounding solution, where the dissolution and precipitation reactions are fully considered between the hydrated products and the mobile ions, and the three phases are involved, including cement paste, aggregates, and interfacial transition zone. The governing equations are achieved by the conservation law of mass and the Maxwell equation, and the constitutive relations are derived by the second law of thermodynamics. Furthermore, the verified model is employed to investigate electrochemical behavior of the concrete structure. The results reveal that the spatial and temporal evolutions of the ion concentrations and the hydrated products are significantly affected by the surrounding solution, the ion diffusion constant and the electric potential applied. Furthermore, an abrupt variation is found for the ion concentration at the concrete-solution interface, showing the critical role of the surrounding solution domain. The present model may provide theoretical guidance in the design and optimization of the concrete structure durability.