Desorption behavior and mechanism of chloride ions in fresh concrete mixtures under electromigration

Abstract

Detecting chloride ions in concrete mixtures is the final checkpoint to assess whether the chloride-ion content of hardened concrete is qualified. This paper devises a method to rapidly detect the chloride-ion content of fresh concrete mixtures based on electromigration and then compares it with traditional detection methods. The test results show that the electrochemical method for analyzing the chloride-ion content of concrete is accurate and suitable for various concrete mixture proportions. Moreover, parameter sensitivity analysis demonstrates the dissolution behavior of chloride ions in the concrete mixture when different detection methods are applied. Further, thermogravimetry–differential thermogravimetry (TG–DTG) analysis and scanning electron microscopy–energy-dispersive spectrometry (SEM–EDS) are used to study the desorption mechanism of chloride ions under the action of an electric field at a micro-level. The results of this paper provide technical means for rapidly detecting the chloride-ion content of fresh concrete mixtures, which is vital to ensuring the durability of concrete structures.