浸泡条件下高韧性水泥基复合材料氯离子侵蚀试验研究

Experimental Study on Chloride Ion Erosion of Engineered Cementitious Composites under Soaking Condition

为探究高韧性水泥基复合材料(ECC)在浸泡条件下抵抗氯盐侵蚀的能力,研究开展了ECC的氯离子侵蚀试验。设置0.26、0.28、0.30三种不同水胶比试件,在5wt%、10wt%、16wt%三种氯盐溶液中分别浸泡12 d、30 d、60 d、90 d,用硝酸银溶液对不同情况下的氯离子侵蚀深度进行测试,以此研究水胶比、氯盐浓度以及侵蚀时间对ECC氯离子侵蚀深度的影响规律。结果表明,水胶比越小,ECC基体内部孔隙越少,基体越密实,氯离子侵蚀深度越小;随着氯盐浓度的增大,基体内外浓度差增加,氯离子侵蚀深度随之增大;随着侵蚀时间的增加,浸泡30 d内氯离子侵蚀深度增加较快,后期随着基体内部一系列反应发生,部分孔隙被填充,基体内部有效氯离子传输通道减少,氯离子侵蚀深度增长速度减小,侵蚀深度总体随时间呈现两阶段增长;最后通过回归分析建立氯离子侵蚀深度的预测模型。

In order to study the ability of engineered cementitious composites(ECC)to resist chloride erosion under soaking condition,the chloride ion erosion test of ECC was carried out.Setting 0.26,0.28 and 0.30 different water-binder ratio test pieces,soaked in 5wt%,10wt%and 16wt%chloride solutions for 12 d,30 d,60 d and 90 d respectively,and tested the chloride ion erosion depth under different conditions with silver nitrate solution,to study the influence of water-binder ratio,chloride concentration and erosion time on the chloride ion erosion depth of ECC.The results show that the smaller the water-binder ratio is,the fewer the internal pores and the denser of ECC,and the smaller the depth of chloride ion erosion.With the increase of chloride concentration,the concentration gradient between the inside and outside of ECC increases,the chloride ion erosion depth increases.With the increases of erosion time,the erosion depth increases rapidly within 30 d of soaking.At the later stage,as a series of reactions took place in the matrix,some pores are filled,and the effective chloride ion transport channels reduces.The growth rate of chloride ion erosion depth decreases,and the erosion depth increases in two stages with time.Finally,the prediction model of chloride ion erosion depth is established by regression analysis.