基于随机细观骨料的钢筋表面氯离子浓度概率分布研究

氯盐侵蚀诱发钢筋锈蚀是导致钢筋混凝土结构耐久性失效的主要因素之一。研究钢筋表面氯离子浓度概率分布对于预测海洋工程的服役性能具有十分重要的意义。通过引入随机厚度的界面过渡区,建立了包含骨料、界面过渡区以及砂浆的三相混凝土细观模型。在此基础上,结合氯离子扩散理论,建立了氯离子扩散细观数值模型。研究结果表明,骨料对氯离子的扩散具有阻碍作用,增加了氯离子的扩散路径。通过对6 000个钢筋表面氯离子浓度的模拟结果进行统计分析,发现:当骨料率为40%(体积分数)时,钢筋表面氯离子浓度呈双峰分布;当骨料率小于40%时,钢筋表面氯离子浓度近似呈正态分布;随着骨料率的增加,钢筋表面氯离子浓度不断减小,变异系数不断增大。

Probability Distribution of Chloride Ion Concentration on Surface of Reinforcing Bar Based on Random Meso-Aggregate

Chloride ion erosion is one of the main factors leading to the durability failure of reinforced concrete (RC) structures. Thus, the study of the probability distribution of chloride ion concentration on the surface of reinforcing bar is of great significance to predict the service performance of marine engineering. By introducing the interface transition zone (ITZ) of random thickness, a concrete meso-model including aggregate, ITZ and mortar was established. Based on the theory of chloride ion diffusion, a meso-numerical model of chloride ion diffusion was established. The results show that the aggregate hinders the chloride ion diffusion and increases the chloride ion diffusion path. According to the statistical analysis of the chloride ion concentration on the surface of reinforcing bar surface by simulated 6 000 groups chloride ion diffusion, when the volume fraction of aggregate ratio is 40%, the chloride ion concentration on the reinforcing bar surface has a bimodal distribution and when aggregate ratio is lower than 40%, the chloride ion concentration on the reinforcing bar surface has a normal distribution. With the increase of aggregate ratio, the chloride iron concentration decreases and the coefficient of variation increases.