Thermodynamics and kinetics evolution of the mass transfer process in concrete composites

Aggressive species from the external environment, such as oxygen, water, chloride, etc., penetrate into concrete and, when they reach the reinforcing steel surface, cause steel corrosion. The transport process of aggressive species in the concrete cover is closely related to the safety assessment, maintenance, reinforcement, and performance-based design of reinforced concrete (RC) structures. Their transport process—especially that of chloride—is typically the results of the physical and chemical interactions between aggressive species and concrete, i.e., diffusion, convection, electromigration, and physical and chemical reactions between the pore solution and the cement hydrate. Therefore, the numerical model of the ionic transport in concrete composites will be introduced in this chapter, including the theoretical equation of ionic transport, the numerical calculation method, and two numerical examples in saturated and nonsaturated concrete.