ABSTRACT
Atmospheric carbon dioxide diffuses into concrete through empty pores in the binder matrix and reacts with the hydrated cement. The reaction lowers the alkalinity of the pore fluid: this can destroy the passive oxide layer on any adjacent steel reinforcement and leaves the steel susceptible to corrosion, Kashino (1984), Saeki et al (1984), Fukushi (1985) and Parrott (1990). Corrosion, being an electro-chemical process, is also dependent upon the conductivity of the concrete surrounding the steel and this, in turn, increases with concrete moisture content. However at moisture contents close to saturation the corrosion rate diminishes due to an insufficient supply of oxygen, Tuutti (1980), Gonzalez (1982).
