对《水运工程混凝土试验规程》中测试氯离子含量方法的几点见解

OPINIONS ON TEST METHOD OF CHLORIDE IONS CONTENT IN "TESTING CODE OF CONCRETE FOR PORT AND WATERWAY ENGINEERING"

在酸溶试样条件下,用铁铵矾NH4Fe(SO4)2为指示剂来测试混凝土中氯离子含量。试验结果表明:测试的精度高,滴定终点明显,而依照《水运工程混凝土试验规程》(JTJ 270-98)用铁矾FeSO4.7H2O作指标剂终点不明显,误差相对较大。同时建议规程补充在测试试样溶液中加有机溶剂,这样可避免沉淀转化。而对水溶性氯离子含量的测定,稀硫酸的含量视实际情况进一步稀释,更有利于铬酸钾的显色范围,提高测试精度。

On condition of acid dissolving test samples, using ferriammonium sulfate as an indicator to test chloride ions content in concrete, the testing results are precise and titration end point is very obvious. Whereas using iron vitriol as an indicator according to “Testing Code of Concrete for Port and Waterway Engineering”（ JTJ 270 - 98 ）, it is found that the error is relatively large and titration end point is blur. Many experiments prove that adding organic solvent to testing liquor is very advantage, because it can avoid deposition developed from transforming. Which is more favorable for coloring of potassium chromate and improving testing precision in using water dissolving sample to test chloride ions, the concentration of sulfuric acid needs to dilute in view of practical situation.