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为研究硫酸盐侵蚀下硫酸根离子在混凝土内的扩散反应规律,利用Fick第二定律建立了硫酸根离子在混凝土中的非线性非稳态扩散反应方程,并运用有限差分法求解该方程,以获得离子在混凝土中的分布规律及因化学反应而消耗的数量。通过数值仿真,模拟浸泡在5.5%浓度的Na2SO4溶液中的混凝土板内硫酸根离子扩散过程。结果表明:硫酸根离子在混凝土板内的扩散速率随着扩散过程进行由快逐渐变慢,边缘处侵蚀离子浓度大于内部浓度,边缘处发生化学反应而消耗的硫酸根离子浓度大于内部。模拟结果为硫酸盐侵蚀下混凝土耐久性损伤分析提供依据。
In order to study the diffusion reaction of sulfate ion in concrete under sulfate attack, the nonlinear unsteady diffusion reaction equation of sulfate ion in concrete was established by Fick’s second law. The equation was solved by finite difference method Ions obtained in the distribution of ions in the law and the number of chemical reactions consumed. Through numerical simulation, the diffusion process of sulfate ion in concrete slab immersed in 5.5% Na2SO4 solution was simulated. The results show that the diffusion rate of sulfate ion in concrete slab gradually slows down with the diffusion process, the ion concentration in the edge is greater than the internal concentration, and the chemical reaction at the edge consumes more sulfate ion than in the interior. The simulation results provide the basis for the durability damage analysis of concrete under sulfate attack.