Numerical Modeling of Initiation and Propagation of Corrosion in Hollow Submerged Marine Concrete Structures

When reinforced concrete structures exposed to marine environments have both saturated and aerated parts, as for instance submerged tunnels or car parks, a macrocell can develop. This may cause an increase in the potential and the corrosion rate of reinforcing steel in the saturated part. The aim of this paper is to study the effects of macrocells during corrosion initiation and propagation through numerical simulations of a wall separating a dry environment from seawater. When steel bars are passive, the macrocell increases the potential of rebars in saturated concrete and promotes steel depassivation. After corrosion initiation, the macrocell increases steel corrosion rate by several orders of magnitude, favouring also corrosion localisation. A sensitivity analysis was carried out to investigate the influence of the main parameters: the models showed that some electrochemical parameters, such as the cathodic Tafel slope of steel polarisation curve, have a strong influence on the results.