| Summary: | According to Fick's second law, the unsteady diffusion equation of sulfate ion is established in concrete. The finite difference method is used to solve the equation to obtain the concentration distribution of sulfate ion in concrete. Based on the number of calcium vanadium, which is produced by the chemical reaction between sulfate ion and calcium aluminate in concrete, the formula is given for calculating the expansion of concrete in the process of calcium vanadium formation. In addition, the corresponding expansion of concrete is calculated from the constitutive relation of concrete stress to assess whether the concrete is cracked. In this paper, the diffusion process, swelling strain, stress change and cracking process in the concrete slab immersed in 2% Na2SO4 solution are simulated by numerical simulation. And the results show that the proposed method can quantitatively describe the damage law of concrete under the sulfate attack.
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