ABSTRACT
The corrosion of steel in concrete is a major cause of degradation in above-ground reinforced concrete structures. The corrosion process (Figure 6.1) is electrochemical and is initiated by changes in the chemical environment at the steel-concrete interface of which there are two main causes: the reduction of the local alkalinity by carbonation and the breakdown of passivity of the reinforcing steel by chloride ions. Both of these are exacerbated by poor construction practices such as low concrete cover to the reinforcement and poor-quality, porous concrete. Reinforced concrete structures made with adequate cover and goodquality concrete are resistant to both the above corrosion-inducing processes for prolonged periods of time. Chlorideinduced corrosion will eventually initiate on structures with good levels of cover and this is the form of corrosion that is normally considered as controllable by cathodic protection.
