Abstract

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Title:: Revised Chloride Ion Diffusion Models of Concrete Bridges Near Coastal Areas Considering Surface Chloride Ion Concentration

Author(s):: HE Hua-nan; FENG Ye; ZHANG Guan-hua; WANG Jia-wei; State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology

Keywords:: concrete structure; chloride ion diffusion model; Fick second law; surface chloride ion concentration; water-binder ratio

Abstract:: In order to research the chloride ion diffusion law of reinforced concrete bridges whose distance from the coast was 5-40 km, a proper chloride ion diffusion model was built, and 25 bridges along Shenyang-Shanhaiguan highway were sampled by the method of drilling core. The relationship between surface chloride ion concentration and water-binder ratio was analyzed. The proportionality coefficient of the measured values and the fitted values of surface chloride ion concentration was brought in to establish the mathematical relationship between surface chloride ion concentration and distance from the coast. The analytic solution of Fick second law was modified combining the time effect of apparent diffusion coefficient of chlorine ion. The revised model was verified by comparing the measured values and the fitted values. The results show that the surface chloride ion concentration of the component is proportional to water-binder ratio, and the proportionality coefficient follows the statistical law of normal distribution. The surface chloride ion concentration of component decreases with the distance from the coast increasing and they follow the exponential relationship. The fitted values calculated by the modified chloride ion diffusion model can envelop most of the measured values, and the fitted results are partial safety.