Steel corrosion in concrete: Determinist modeling of cathodic reaction as a function of water saturation degree

The prediction of the long-term behavior of reinforced concrete structures involved in the nuclear waste storage requires the assessment and the modeling of the corrosion processes of steel reinforcement. This paper deals with the modeling of the cathodic reaction that is one of the main mechanisms of steel rebar corrosion. This model takes into account oxygen reduction and oxygen diffusion through a diffusion barrier (iron oxide and/or carbonated concrete) as a function of water saturation degree. It is demonstrated that corrosion rate of reinforcement embedded in concrete with water saturation degree as low as 0.9 could be under oxygen diffusion control. Thus, transport properties of concrete (aqueous and gaseous phase, dissolved species) are key parameters that must be taken into account to model electrochemical processes on the reinforcement.