Introduction The corrosion of reinforcement bars and prestressing strands in concrete structures is a significant issue particularly in coastal environments. The conventional wisdom is that time to initiation of such corrosion is governed by the rate of ingress of chlorides and other aggressive species from the environment through the concrete to the reinforcement. Methods The present paper reviews, briefly, the conventional wisdom and reviews a number of observations recently made about the reinforcement corrosion problem in marine environments. Also presented are the results of a long-term experimental program in which real concretes covering a wide variety of concrete mixes, mixing waters and water-cement contents were exposed to actual seawater conditions. This includes concretes made with high calcium carbonate content and also contents with high chloride content. This allowed completely new experimental results obtained for real concretes in actual seawater exposures. Conclusion The experimental results show that the time to initiation of corrosion of reinforcement in concretes made with high salt contents depends on the composition of the concrete and specifically is delayed for concretes with high calcium carbonate content. The effect of higher cement content, water cement ratio and the presence or absence of salt water in the concrete mix also are presented and are less significant.