Effect of Chloride Exposure Condition on the Performance of Concretes Containing PFA

Over the past number of decades the use of different supplementary cementing materials have been investigated, with a view to increasing the resilience of reinforced concrete to chloride-induced corrosion. The slow nature of chloride-ion ingress has meant much of the information available on the relative performance of different concretes has been derived from accelerated testing, with the majority of these tests conducted under fully saturated conditions. While there is merit to such practices, there is also a need to examine the relative performance of different concretes under unsaturated conditions. This need is highlighted by the fact that reinforced concrete elements in the splash, spray and tidal zones of marine structures, which are subject to wetting and drying cycles, are most susceptible to reinforcement corrosion. This paper examines the effect of different wetting and drying cycles on the relative performance of OPC self-compacting concrete, and self-compacting concrete containing PFA. This was achieved through three sets of salt fog chamber tests, each with different wetting and drying cycles. It was found that, when compared to the OPC option, the relative chloride ingress resistance of the OPC + PFA concrete reduced when the degree of drying in the test increased. This indicates that fully saturated tests may somewhat overestimate the practical benefits of incorporating PFA into concrete in chloride rich environments.