Chloride penetration resistance of concrete under dual effects of calcium leaching and stress

Chloride penetration is one of the main causes of failure of reinforced concrete structures, especially in undersea tunnels, which is also accompanied by stress and seepage-induced calcium leaching. The chloride penetration resistance of concrete under the single and dual effects of stress and calcium leaching were investigated in this work. The microscopic mechanisms were evaluated using scanning electron microscopy and X-ray diffraction analysis. The results showed that the chloride diffusion depth and chloride content increased linearly with the stress level in the tensile zone and decreased linearly in the compressive zone; the change was more obvious in the tensile zone. At stress levels of 15%, 30% and 45%, the diffusion depth in the tensile zone increased by 11.4%, 36.6% and 43.5%, respectively, while the change ratios of chloride content were 1.2%, 11.2% and 19.4%. No significant synergistic effect between stress and calcium leaching on the chloride diffusion depth was found, but the effect on chloride content was obvious, especially when the tensile stress level was below 15% and the compressive stress level was above 30%, for which the differences caused by considering the synergistic effect or not were approximately 6% and 15%, respectively.