Influence of cement content on corrosion resistance

The minimum cement content requirement given in codes of practice over the years to ensure durability of concrete is being increasingly questioned. Of all the durability problems related to concrete structures, corrosion of reinforcing steel is the single most prevalent deteriorating process. This paper describes a study undertaken to determine the influence of variation in cement (binder) content at fixed water/cement ratio on carbonation- and chloride-induced reinforcement corrosion. Cement (binder) content was varied above and below the limits given in current European standards in the tests. The fines content (particles < 75 μm) of some cement-reduced mixes was maintained with the inclusion of a limestone filler as part of the sand content. The results indicate that cement reduction below the given minimum cement contents in current standards has insignificant influence on the overall carbonation-induced reinforcement corrosion process. Moreover, cement content has very little influence on the overall chloride-induced reinforcement corrosion process except the possible better performance of cement-reduced concrete with filler. It is suggested that the attention traditionally given to minimum cement content in determining reinforcement corrosion resistance may be disproportionate to the effective influence of this parameter.