Multi-species reactive transport modeling of electrochemical corrosion control in saturated concrete structures including electrode reactions and thermodynamic equilibrium

The ionic migration in concrete determines the efficiency of electrochemical corrosion control of reinforced concrete structures, such as electrochemical chloride extraction, electrochemical realkalization, and impressed current cathodic protection. In this study, a numerical model of the multi-species reactive transport in saturated concrete structures with electrochemical corrosion control is proposed. The proposed model includes ionic transport, thermodynamic equilibrium and electrode reactions. The electrode reactions at the surface of reinforcing steel are considered using the Tafel equation. The thermodynamic model is adopted to express the physical and chemical reactions between pore solution and hydration products. The diffusivity coefficient of material based on the variation of porosity is updated at the end of each time step of the numerical model. Additionally, a laboratory experiment is conducted to verify the numerical model. The numerical results clearly show that the applied electrochemical corrosion control based on the numerical model is capable of preventing the initiation of corrosion, avoiding the hydrogen embrittlement, arresting the Cl⁻ penetration, and improving the pH value and CH content adjacent to the reinforcing steel.