无机盐种类对混凝土电阻率的影响

对于电网中接地金属的保护课题,考虑利用混凝土包裹扁钢制成接地模块的形式来解决。由于混凝土本身具有较高的电阻率,不能达到良好的接地效果,为此针对这一问题,参考化学降阻剂的成分,以向混凝土中添加无机盐的形式来达到降低其电阻率的目的。试验研究了9种常见的无机盐对混凝土电阻率的影响,分别为阳离子K~+、Na~+、Mg~(2+)和阴离子SO_4~(2-)、Cl~-、CO_3~(2-)的两两相互组合。同时依据氯盐含量对于钢筋腐蚀速率的影响关系,设定盐的添加剂量均为水泥用量的4%。利用无添加剂混凝土组作为对照,分析电阻率降低的效果。试验结果表明添加无机盐可降低混凝土的电阻率,且得出了这9种无机盐在添加相同质量分数时降低混凝土电阻率效果的优劣关系;其中效果最好的无机盐添加剂为K_2SO_4,添加后混凝土电阻率降低至不添加时的37.9%。

The influence of the species of inorganic salt on concrete resistivity

For the issue of grid grounding metal protection, considering solving it in the form of steel being wrapped up with concrete which is similar to the earthing module. But this cannot achieve good grounding effect for concrete itself has high resistivity, aiming at this problem and referring to the chemical element of drag reduction agent, the method of adding inorganic salt to concrete to reduce the resistivity is used. A study of how the sort of inorganic salt additives affect the resistivity of concrete is conducted, with a total of nine kinds which are mutual combination between cationic K+, Na+, Mg2+ and anion SO42-, Cl-, CO32-. And on the basis of chlorine salt content for the influence of the steel bar corrosion rate, a 4% added dose of salt is determined by weight of the cement. For purpose of eliminating the bad influence, there are three specimens being made of the same composition and the results are taken the average. The concretes without additives are made as comparison, and the effect of resistivity reduction is analyzed. The test result shows that adding inorganic salt can reduce the resistivity of concrete, meanwhile the resistivity reduction relationship of these nine kinds of salt when adding the same mass fraction was found. Among these kinds, K2SO4 is the most effective, and after being added the resistivity of concrete decreases to 37.9% in comparison with those without salt.