Calculation of Chloride Ions Transportation in Concrete Considering Convection

Abstract:

By dividing the transportation area of chloride ions in concrete into convection diffusion coupling and diffusion areas. Separation of variables method and variable substitution method have been used to resolve chloride ions transportation equations of coupling and diffusion areas, respectively. Analytical solutions of the chloride ions transportation in concrete have been presented considering convection. Based on the stability analysis of coupling area solution, the scopes of calculation parameters are determined: superposition times n and chloride ions influence depth l must be no less than 100 and 1 000 mm, respectively. A positive correlation between convection depth, seepage velocity and initial chloride content with the accumulation of chloride ions in concrete was found by calculations and analyses. With the increase of time, the chloride ion concentration differences increase with the increase in convection depth and seepage velocity, while decrease with the increase in initial chloride content. Accuracy of the calculation model is verified by fitting the chloride ions concentration in a 38 years concrete suffering from convection.