Cathodic protection of reinforcement in carbonated concrete

The protection mechanism of cathodic protection applied to carbonated concrete structures have been investigated. Tests were carried out on reinforced concrete specimens with alkaline concrete, carbonated concrete and carbonated concrete with 0.4% chloride by cement weight. Cathodic current densities ranging from 2 to 10 raA/m2 were applied to the reinforcement. Potential measurements and four hour depolarization tests during the first year are shown. Changes in pH in the vicinity of the steel surface have been monitored by means of activated titanium electrodes. On the basis of the experimental results, the beneficial effects of cathodic current are discussed. The importance of realkalization of concrete in contact with the reinforcement and repassivation of steel in order to achieve stable protection conditions is shown. Protection conditions are discussed to provide design parameter and protection criteria of steel in carbonated concrete.