Aspects of long-term durability of reinforced concrete structures in marine environments

Much concern exists about the apparently short durability of reinforced concrete structures in marine environments. However, there are many examples of structures that have survived for long periods of time with little evidence of reinforcement corrosion. Some of these were made with seawater as mixing water. Others had very little concrete cover. Detailed examination has revealed that reinforced concrete structures made with fine or coarse aggregate consisting of calcium carbonates such as limestone or seashells or with non-reactive dolomite have extended times to commencement of corrosion initiation and to active corrosion. The reasons for this are explored herein. In addition it is shown that some structures can have serious localized reinforcement corrosion without obvious exterior signs such as concrete cracking and delamination. This requires urgent research.