Influence of Water-Cement Ratio and Cover Thickness on Chloride Extraction of Reinforced Concrete

Abstract

Chloride ions can infiltrate concrete by a variety of ways, including admixtures, contaminated sand, or external penetration. When the concentration of chloride ions reaches a critical level, the corrosion begins. This article reports on a study that evaluated the method of electrochemical extraction of chloride ions for the rehabilitation of concrete structures with reinforcement corrosion. The authors investigated the influence of the concrete cover and the water-cement ratio (w/c) in the efficiency of the method by determining the initial and the final chloride content. Electrochemical impedance spectroscopy and the corrosion potential were used to monitor the reinforcement electrochemical behavior during the chloride extraction. The test results verified that the method successfully extracted chloride ions. On average, 77% of the content of initial chloride ions at a distance of 0.5 cm from the surface (depth where the slices had been extracted) were removed. The study used tap water as the electrolyte, which caused high polarization of the reinforcing bars during the extraction; the authors recommend an alkaline solution for future studies. The porosity of the concrete was not affected by the electrochemical chloride extraction.