氯盐环境下混凝土氯离子传输和钢筋锈蚀研究

Study on Chloride Ion Transport in Concrete and Steel Corrosion in Chloride Environment

通过对16组带裂缝100×100×400mm的短梁进行在氯盐溶液的干湿循环试验,以裂缝宽度、混凝土保护层厚度和钢筋直径为变量,研究不同裂缝宽度的钢筋混凝土裂缝周围和沿裂缝深度的氯离子含量,以及裂缝底端钢筋锈蚀长度,探讨氯离子传输规律;钢筋锈蚀长度的影响因素;并提出钢筋锈蚀长度预测模型。结果表明:氯离子在带裂缝混凝土中以二维扩散的方式扩散,氯离子在裂缝周围40~60mm区域的二维扩散效应表现得更加显著;混凝土深度为10mm范围内氯离子浓度随裂缝增大的趋势相对平缓,当深度>10mm后,其趋势变大;裂缝宽度对钢筋锈蚀长度影响最大,当裂缝宽度w<0.3mm时,钢筋锈蚀长度的预测值与试验值符合程度较好,钢筋锈蚀长度预测模型具有一定合理性。

Through the dry-wet cycle test of 16 groups of cracked 100×100×400 mm short beams in the chloride salt solution,the crack width,the thickness of the concrete protective layer and the diameter of the steel bar were used as variables to study the cracks around the reinforced concrete cracks with different crack widths.The chloride ion content along the depth of the crack and the length of the steel corrosion at the bottom of the crack were discussed.The chloride ion transport law and the influence factors of the corrosion length of the steel were discussed.The prediction model of the steel corrosion length was proposed.The results show that the chloride ion diffuses in the two-dimensional diffusion mode in the cracked concrete,and the two-dimensional diffusion effect of chloride ion in the 40~60 mm region around the crack is more significant.The chloride ion concentration increases with the crack in the concrete depth of 10 mm.The trend is relatively flat.When the depth is greater than 10 mm,the trend becomes larger;the crack width has the greatest influence on the corrosion length of the steel.When the crack width is at w<0.3 mm,the predicted value of the corrosion length of the steel is in good agreement with the experimental value,and the steel corrosion is good.The length prediction model has certain rationality.