A review of chloride-induced steel corrosion in coastal reinforced concrete structures: Influence of micro-climate

The corrosion initiation by chlorides for reinforced concrete (RC) structures is influenced by the nature of chloride transport through concrete and the chloride threshold. These two properties vary with the chloride exposure conditions and concrete properties. Since most lab-scale experiments are conducted for isolated exposure cases under controlled conditions, the coupling effect of micro-climate, such as temperature, wind features, carbon dioxide ingress, wet/dry cycle durations, and rainfall, on corrosion initiation is not thoroughly discussed. This review addresses the role of micro-climate in both chloride transport and chloride threshold for corrosion initiation in different marine exposure zones. The mechanism of coupled interactions and the influence of concrete mixes are discussed. The review emphasises the need to standardize chloride-induced corrosion experiments that consider micro-climate conditions to ensure the comparability of data. A limited understanding of chloride-induced steel corrosion risk is evident in alternative binders that have recently been developed. Finally, the review provides future research directions to clarify some coupled interactions that have not been well understood.