Chloride diffusion and reinforcement corrosion in marine exposed concretes containing pulverized-fuel ash.

Steel reinforced concrete specimens, with pulverized-fuel ash (pfa) contents in the range 0 to 50% and designed to equal strength grade and workability, were exposed in the tidal zone of the BRE seawater exposure site following various periods of initial curing. Total chloride concentration profiles and reinforcement bar weight losses were determined on specimens retrieved after exposure periods of 1 and 2 years. Chloride diffusion coefficients were calculated from the chloride concentration data. The results show that in both pfa concrete and opc concrete the rate of penetration of chloride ions and subsequent corrosion of steel reinforcement are increased as the duration of initial curing is curtailed. However, these effects become less pronounced as the length of exposure is extended. Both the rate of penetration of chloride ions and the consequent weight loss of reinforcing bars due to corrosion were lower in pfa concrete than in the control opc concrete and decreased with increasing pfa content. For all specimens a correlation was established between reinforcing bar weight loss and total chloride concentration at the location of the steel, enabling a threshold value for chloride content to initiate corrosion to be determined. (A)