干湿循环作用下高韧性水泥基复合材料抗氯离子腐蚀寿命预测

Toughness Cement-Based Composites Under Dry and Wet Cycles

为了预测干湿循环下高韧性水泥基复合材料(ECC)的使用寿命,首先,基于氯盐溶液传输边界条件、氯离子扩散侵蚀边界条件等建立以饱和度和时间为变量的氯离子侵蚀模型;然后,考虑腐蚀龄期、温度、物理吸附、化学结合以及饱和度等因素对混凝土的影响,并对氯离子扩散系数进行修正;最后,结合试验数据模拟氯离子侵蚀过程。试验结果表明,随着干湿循环次数的增加,ECC表层氯离子浓度和氯离子侵蚀深度随之增加;随着腐蚀龄期的增加,钢筋发生锈蚀的范围越来越大。当混凝土保护层厚度为50 mm时,内部钢筋不发生锈蚀的临界年限为7 a。

In order to predict the service life of high-toughness cement-based composites under dry and wet cycles,firstly,a chloride ion erosion model with saturation and time as variables was established based on the transport boundary conditions of chloride salt solution and chloride ion diffusion erosion boundary conditions.Then,considering the corrosion age,temperature,physical adsorption and chemical bonding,saturation and other factors,the chloride ion diffusion coefficient is modified.Finally,chloride ion erosion is simulated with experimental data.The experimental results showed that the chloride ion concentration and the chloride ion erosion depth of ECC surface increased with the increase of the number of dry and wet cycles.With the increase of corrosion age,the scope of corrosion of steel bars becomes larger and larger.When the thickness of the concrete protective layer is 50 mm,the critical age of the internal steel bar without corrosion is 7 a.