Chloride profile characterization by electron probe microanalysis, powder extraction and AgNO3 colorimetric: A comparative study

• Published in: Construction & building materials Vol. 341; p. 127892
• Main Authors: Fu, Chuanqing, Li, Siyao, He, Rui, Zhou, Kewen, Zhang, Yun
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 25.07.2022
• Subjects: Acid-soluble chloride content; AgNO3 colorimetric analysis; Chloride profile; Electron probe microanalysis (EPMA); Water-soluble chloride content; Acid-soluble chloride content; Electron probe microanalysis (EPMA); AgNO3 colorimetric analysis; Water-soluble chloride content; Chloride profile
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2022.127892

•The chloride content of cement mortar with different supplementary cementitious materials (SCMs) was determined by electron probe microanalysis (EPMA), powder extraction, and AgNO3 colorimetric analysis.•The color boundary chloride content determined by 0.1 M AgNO3 is 1.39 times higher than that of 0.035 M AgNO3.•The chloride profile determined by EPMA is close to acid-soluble chloride content while the water-soluble chloride content determined by the method used in this study is 0.71 times that of EPMA-determined chloride content. In this study, the chloride profile of cement mortar with various supplementary cementitious materials after 100 d immersion in 5% NaCl solution was characterized by electron probe microanalysis (EPMA), mortar powder extraction, and AgNO3 colorimetric methods. The results show that the EPMA determined chloride profile is very close to the acid-soluble chloride content while the water-soluble chloride content is 0.71 times that of EPMA determined. It is found that the chloride penetration depth determined by AgNO3 solution is affected by the concentration of AgNO3. The high AgNO3 results in low measured chloride penetration depth. The chloride content at the color boundary determined by 0.1 M AgNO3 solution is 1.39 times that of the result obtained from 0.035 M AgNO3 solution. Due to the retention effect by bound chloride, the apparent chloride diffusivity determined by water-soluble chloride content is higher than that of EPMA and acid-soluble chloride determined diffusivities. This work can be used to broaden the understanding in chloride transportation and determination method of the community.