混凝土中硫酸根离子扩散系数劣化效应研究

Research on the degradation effect of sulfate ion diffusion coefficient in concrete

鉴于硫酸根离子在扩散过程中会与混凝土材料的水化产物发生化学反应,在扩散方程中引入关于扩散系数的化学反应劣化效应系数,建立了考虑化学反应因素影响的混凝土硫酸根粒子扩散确定性理论模型。该模型解决了Fick第二定理在混凝土中的适应性问题,通过与实验结果进行比较,验证了确定性理论模型可以较好地预测硫酸根离子浓度均值。考虑到混凝土材料在其形成之初的微孔洞、微裂缝等初始缺陷具有随机性,采用高斯随机分布来描述初始扩散系数,研究建立了考虑化学反应因素影响的混凝土硫酸根离子扩散随机性理论模型。通过与实验值对比,验证了随机性理论模型能够较好地预测出硫酸根离子浓度的分布范围。

As the sulfate ions react with the hydration products of concrete material in the diffusion process,the coefficient of chemical reaction degradation effect of diffusion coefficient is introduced to the equation of diffusion and the deterministic theory model of sulfate ion diffusion is established based on influencing factor of chemical reaction being taken into consideration. Compared with the test result,the present model can be used to predict the mean value of sulfate ion concentration and it solves the problem of adaptability of Fick＇s second law of diffusion in concrete. Considering the micro holes with randomness at the beginning of the formation of concrete material,the Gaussian random distribution was used to describe the initial diffusion coefficient and the stochastic theory model of sulfate ion diffusion is established considering the influencing factor of chemical reaction. Compared with the test result,the present model can be used to predict the range of sulfate ion concentration.