Observations About the Performance of Reinforcement in Marine Environments

The corrosion of reinforcement bars and prestressing strands in concrete structures is a significant issue in coastal environments. The conventional wisdom is that time to initiation of such corrosion is governed by the rate of diffusion of chlorides and other aggressive species to the reinforcement. However, the rate of reinforcement corrosion is not significantly affected by the presence of chlorides. A review is given of recent observations of the lack of serious reinforcement corrosion for some older structures in marine environments. These and new experimental results for concretes in actual seawater exposures show that the time to initiation of corrosion of reinforcement is delayed for concretes with high calcium carbonate content. Observations from on-gong experimental investigations for the effect of low heat cement, water and aggregate cement ratios and the level of salinity of salt water in the concrete mix also are presented.