Numerical study of carbonation and its effect on chloride binding in concrete

Under marine and industrial-polluted environments, reinforced concrete structures (RC structures) are attacked by carbonation and chloride penetration; both can cause deterioration of steel and concrete. Thus their coupled effect will definitely intensify the serious corrosion of RC structures. This work evaluates the chloride binding and the subsequent species diffusion process incorporating with carbonation rate, under the condition of chloride-contaminated first and then carbonated, so as to explore the mechanism of carbonation influence on chloride binding. Hence, the unique and specific concept of carbonation rate, to elaborate the synergetic effect of different crucial environmental factors on carbonation, is adopted innovatively. The impact of the reorganization of physical microstructures is elucidated. Additionally, both the influence of dissolution threshold of bound chloride and concentration of carbon dioxide on binding, together with their incidence analysis are investigated. It is proved that this specialized carbonation rate, as a fundamental criterion, could be utilized to quantify bound chloride and corresponding debound process in concrete exposed to both chloride and carbonation environments.