Development of a Rapid Test Bar for Quantitative Detection of Chloride Ions in Fresh Concrete

Abstract

Due to the shortage of natural raw materials, many practitioners proposed to make concrete from desalinated sea sand. To reduce the risk of abuse of uncleaned sea sand, we proposed a new rapid test bar to detect chloride ions in fresh concrete quantitatively. The test bars were prepared by mixing silver chromate with cotton fiber. By virtue of the high liquid-absorbent capacity of cotton fiber, the chloride-contained liquid in fresh concrete will rapidly enter into the test bar and react with the silver chromate to finally show a certain coloring height, which corresponds to the actual chloride content. In order to optimize the preparation process, the color rendering, testing time and stability of test rods under different mixing ratios and conditions were investigated. The relationship between color height and chloride content was established, and an auxiliary card is prepared for user-friendly calculation of chloride content. The results showed that the best performance of the test bar was obtained under the following conditions: mass concentration of silver chromate 5.0g/L, soaking time 1 min, drying temperature 50℃ and content of discolored silica gel 0.5g/ root.