硫酸盐对混凝土侵蚀过程的细观数值分析

Mesoscopic numerical analysis of sulfate attack on concrete

硫酸盐侵蚀作为混凝土耐久性损伤的一个重要方面,日益受到人们的普遍关注。根据Fick第二定律和化学反应动力方程,建立了细观层面硫酸盐对混凝土侵蚀过程的数值分析方法。以混凝土随机凸多边形骨料模型为基础,利用Matlab程序对有限元软件进行二次开发,建立了基于扩散-化学反应的硫酸盐对混凝土侵蚀过程的细观数值分析方法,并与试验结果进行了对比。结果表明:硫酸盐侵蚀过程细观数值方法得到的模拟结果与试验结果吻合较好,可以有效模拟硫酸盐对混凝土的侵蚀过程;距混凝土表面一定深度范围内,SO_(4)^(2-)浓度随表面SO_(4)^(2-)浓度的提高而增加;砂浆中SO_(4)^(2-)扩散系数是影响混凝土内SO_(4)^(2-)最大侵蚀深度的主要因素;界面过渡区厚度对硫酸盐环境中混凝土损伤的影响较小。

As an important aspect of concrete durability damage,sulfate corrosion,has been paid more and more attention.According to Fick′s second law and chemical reaction dynamic equation,a numerical analysis method of sulfate corrosion on concrete at meso-scale is established.Based on the random convex polygon aggregate model of concrete,the finite element software is developed by Matlab program,and the meso numerical analysis method of sulfate corrosion process on concrete based on diffusion reaction is established,and the results are compared with the test results.The results show that the simulation results obtained by the meso numerical method of sulfate erosion process are in good agreement with the experimental results,and can effectively simulate the sulfate erosion process of concrete.The SO_(4)^(2-) ion concentration of concrete increases with the increase of SO_(4)^(2-) ion concentration in a certain depth range.The diffusion coefficient of SO_(4)^(2-) ion in mortar is the main factor affecting the maximum erosion depth of SO_(4)^(2-) ion.The thickness of interface transition zone has little effect on concrete damage in sulfate environment.