Reinforced concrete slabs were cast with a concrete cover of 20 mm. The water-to-cement ratio was 0.40, and the concrete slabs were either uncracked or precracked. A simulated crack 0.2 or 0.4 mm wide was formed transverse to the axis of the reinforcing bar during the casting. Two types of commercial corrosion inhibitors were added to concrete mixtures for corrosion protection. Slabs were placed about 1 m below high tide at the Treat Island, Maine, USA, natural marine exposure site. The specimens were visually inspected and the corrosion rates were measured annually using the linear polarization technique. Some of the concrete slabs were broken open after 12 months of exposure and corrosion damage was evaluated. Water-soluble chloride content analysis was performed at this time. After three years of exposure, it was found, that both corrosion inhibitors were effective in reducing the corrosion rate for uncracked concrete slabs, but relatively ineffective in preventing localised corrosion of reinforcing steel in the crack area for precracked concrete slabs.
Cement and Concrete Composites Journal (25) Theme Issue on Concrete Durability (2003).