Durability study of seawater and sea-sand concrete under the combined effects of carbonation and chloride redistribution

Journal article, 2024

This study presents experimental and numerical investigations to comprehensively assess the impact of carbonation on the durability of chloride-blended seawater and sea-sand concrete. It reveals that carbonation leads to a reduction in pH and results in chloride redistribution along the carbonation depth. The microstructure of concrete after carbonation exhibits increased compaction, reduced porosity, and a refined pore structure. Rebar corrosion in this case is initiated by the excess of chloride ions, as proved by Raman results showing that corrosion product is composed of β-FeOOH. A mathematical model considering several affecting factors was proposed to predict the chloride redistribution in seawater and sea-sand concrete exposed to a carbonation environment, and the numerical results were fitted well with the experimental data. The initiation time for corrosion of the steel rebar is markedly shortened due to the combined effects of carbonation and chloride redistribution. It is verified that the ratio of [Cl−]/[OH−] is a key parameter in predicting corrosion initiation for chloride-blended concrete exposed to carbonation condition. The obtained results are expected to promote the resource utilization of seawater and sea-sand concrete in practical engineering.