Influence of mortar resistivity on the rate-limiting step of chloride-induced macro-cell corrosion of reinforcing steel

The influence of mortar bulk resistivity on the kinetics of chloride-induced macro-cell corrosion of the reinforcement was experimentally studied. It was found that the corrosion process was limited by a combination of anodic, ohmic and cathodic control for the geometrical conditions tested (small anodes (Ø 6mm) and large cathode-to-anode ratio (685)). The cathodic partial process was independent of the bulk resistivity. Both the anodic and the ohmic partial processes were influenced by local conditions around the anode but were not directly related to the bulk concrete resistivity. The findings indicate that a unique relationship does not exist between bulk concrete resistivity and the corrosion rate for chloride induced macro-cell corrosion.