普通硅酸盐混凝土中临界氯离子浓度的试验研究

为得到含氯环境下普通硅酸盐混凝土中钢筋的开始腐蚀时间,首先应掌握的一个重要参数是临界氯离子浓度,此参数因受多种因素影响而数值分布较广。本文基于在脱钝过程中钢筋腐蚀电位集中体现了多因素的综合作用的观点,通过以下三部分工作对临界氯离子浓度进行了研究:首先,利用静电位法,在模拟溶液中测试了氯离子浓度与点蚀电位之间的关系,电位的变化范围取-350￣ 100 mV(SCE);然后,将钢筋混凝土试块放置在三种典型环境中(干燥、湿润、浸润环境),分别测试了三种环境下钢筋腐蚀电位的分布范围;最后,基于钢筋脱钝的两个必要条件:足够小的混凝土电阻以及腐蚀电位超越点蚀电位,得到针对三种腐蚀环境的以占水泥用量比例表示的总氯离子浓度取值。

Experimental study on chloride threshold levels in OPC

In order to predict the time of corrosion initiation of reinforcement in concrete under chloride-containing environment,one of the most important parameters is the critical chloride threshold level,which is influenced by many factors.The present work is based on the idea that the corrosion potential of the reinforcement may include the contribution of the different parameters involved in depassivation.First,potentiostatic tests were performed on reinforcement submerged in simulated pore liquid with the range of potentials from-350 to 100 mV(SCE),to obtain the relationship between chloride contents and pitting potential.Second,reinforced concrete specimens were placed in three typical environments,namely dry,saturated and submerged environments,and the corrosion potential distribution of reinforcement under different environments was investigated.Third,based on the two necessary conditions for corrosion initiation,i.e.,sufficiently low concrete resistance and corrosion potential exceeding the pitting potential,the total chloride contents relative to the weight of cement were provided corresponding to the three typical environments.