Corrosion inhibitors for high performance reinforced concrete structures

In recent years there has been considerable interest in the development of additives and admixtures which reduce or eliminate the ingress of chloride ions into reinforced concrete. One method of increasing the tolerance of RC structures to the presence of chloride ions is the application of corrosion inhibitors. These materials interfere with one or more stages of the corrosion process reducing the overall rate of corrosion. This paper presents the results of a study of two corrosion inhibitors, an admired anodic inhibitor (calcium nitrite) and a commercially available surface applied 'penetrating' inhibitor (a modified amino alcohol). Tests on three concrete mixes were used to investigate the influence of the admixed inhibitor on the workability, set characteristics and 28-day strength of fresh and hardened concrete. The corrosion behaviour of steel bars embedded in equivalent concrete mixes were also examined and the ability of both corrosion inhibitors to suppress corrosion was investigated as a function of time, depth of cover and concrete duality. It is concluded that over the time scale of these experiments both corrosion inhibitors were successful in reducing the rate of reinforcement corrosion.