Influence of cement composition on concrete durability in chloride–sulfate environments

The poor durability performance of reinforced concrete structures is a major problem facing the construction industry throughout the world. It IS estimated that more than $200 billion will be required to repair and rehabilitate deteriorated concrete structures in the USA. Similarly, it is estimated that more than £2 billion will be needed to repair deteriorated concrete structures in the UK Also, considerable resources have to be diverted towards the repair of deteriorated concrete structures in the countries along the Arabian Gulf. Concrete deterioration, worldwide, is mainly attributed to reinforcement corrosion that is caused by chloride ions. However, the effect of other ions, particularly sulfates, on reinforcement corrosion has not been adequately studied. Reinforced concrete structures in marine environments and those built in ‘sabkha’ soils are exposed to both chloride and sulfate salts The combined presence of these two ions may accelerate reinforcement corrosion. Cement chemistry may also Significantly influences the mechanisms of reinforcement corrosion. The quantity of C3A and the alkali content of cement effects its chloride-binding capacity. While considerable research has been conducted on the effect of C3A content of cement on its chloride-binding and reinforcement corrosion, meagre data exist on the effect of cement alkalinity on chloride-binding, while no study has been conducted to evaluate the effect of cement alkalinity on reinforcement corrosion. [Continues.]