Assessment of two-dimensional diffusions of sulfate ions in concrete based on one-dimensional condition

Abstract

A method to link one- and two- dimensional diffusion coefficient models of sulfate ions in concrete is proposed. The method was established on the basis of one-dimensional as well as two- dimensional diffusion tests under different concrete strengths, different sulfate solution concentrations and different immersion periods. Based on the test results, a new one-dimensional diffusion coefficient model related to concrete strength, sulfate solution concentration and immersion period was established. Then, it was found that the two-dimensional sulfate diffusion was not simply the superimposition of two one-dimensional ones. The relationship of 1.33 times of the one-dimensional diffusion coefficient was obtained in the two-dimensional diffusion direction under multi-factor conditions. At last, based on the one-dimensional diffusion coefficient model and 1.33 times relation, a new two-dimensional diffusion coefficient model was proposed. Complying with the Fick's second law, based on the two-dimensional diffusion coefficient model established above, the sulfate ion concentration of each point under muti-factor conditions in two-dimensional diffusion direction can be obtained, which also verified the proposed diffusion coefficient model.