ABSTRACT

Carbonation is a continuous process by which atmospheric CO2 enters the cover zone due to a concentration difference and diffuses inwards(14). The result of this is that the pore fluids become neutralised by carbonic acid. In itself, this has no practical effect on the concrete fabric but the passivity of normal steel reinforcement is no longer maintained and corrosion will ensue, provided there is sufficient moisture to support it. The latter point is important since, generally, there will not be sufficient moisture indoors for significant corrosion to occur, even though higher CO2 concentrations and lower cover depths mean that the conditions for carbonation-induced corrosion are present inside most structures.