西部氯盐渍土介质中混凝土的氯离子扩散性

Chloride diffusion in concrete in a west chlorine saline soil medium

为研究西部氯盐渍土介质中混凝土的氯离子扩散性,采用实验分析、微观扫描、理论预测相结合的方法,分析混凝土中氯离子含量与分布规律、氯离子对流区深度与峰值含量、表层氯离子含量时变规律以及试件表层微观形貌,预测既定混凝土保护层厚度处达到钢筋锈蚀临界氯离子浓度所需时间。研究结果表明,沿扩散深度混凝土中自由氯离子含量与总氯离子含量均呈现出先增长后降低的趋势,二者具有很好的线性关系;存在明显的氯离子含量峰值,随浸泡时间的变化较小;随着浸泡时间的增加,对流区深度逐渐加大,表层氯离子含量逐渐增加,混凝土中Friedel’s和Cl元素逐渐增多。理论分析结果显示,氯离子扩散系数随着扩散深度增加而增大,随浸泡时间增加而减小,使用寿命预测结果与工程实际混凝土结构腐蚀情况吻合较好,预测模型可用于西部氯盐渍土介质中混凝土结构使用寿命预测与分析。

In order to study chloride diffusion in concrete in a west chlorine saline soil medium,experimental analysis,micro scanning and theoretic prediction were applied.The main contents included chloride content and distribution,maximum content and convection zone depth,time dependence of free chloride content and micro morphology in the surface concrete,and prediction of experienced time to get critical chloride concentration for steel corrosion at the given concrete cover depth.The study results shows content of free chloride and total chloride increase first and then decrease with the erosion depth,better linear relationship appears between them.Chloride peak content exists and changes slightly with the soaking period.However,convection zone depth increases,chloride content in the surface concrete grows,Friedel's salt and chloride element in the surface concrete gets more with the increase of soaking time.Theoretic analysis results indicate diffusion coefficient increases with the increase of erosion depth and decreases with the increase of soaking period.Predicted result of service life agrees with the actual corrosion situation of concrete structures,and prediction model for service life can be used to predict and analyze service time of concrete structures in the west chlorine saline soil medium.