Relationship between water-soluble and free chloride concentrations in cement-based materials

Abstract

Water extraction and pore solution expression methods are often used to measure chloride concentration in cement-based materials (respectively, named as Cw and Cf). Three mathematical expressions (Cw = aCfb, Cw = aCf + b and Cw = aCf) have been used to describe the relationship between water-soluble and free chloride obtained with water extraction and pore solution expression methods. Statistical analysis of published data along with the results of this study showed that equations Cw = Ef + b and Cw = aCfb described the relationship very well with similar relative coefficients. However, Cw = aCf resulted in unsatisfactory relative coefficients in some cases. There are numerous standards for water extraction methods, and most of them have demonstrated good repeatability. Different extraction methods result in different constants for the three equations. For comparable results, the extraction procedures should be kept the same.