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

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

Author(s): Paulo J. M. Monteiro, Paulo Helene, Idalina Aoki, Paulo Barbosa, and Eliana Monteiro

Publication: Materials Journal

Volume: 102

Issue: 1

Appears on pages(s): 9-14

Keywords: corrosion; reinforced concrete; water-cement ratio

Date: 1/1/2005

Abstract:
The present work evaluates the method of electrochemical extraction of chloride ions for the rehabilitation of concrete structures with reinforcement corrosion. The influence of the concrete cover and the water-cement ratio (w/c) in the efficiency of the method was studied 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, removing, 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). The electrochemical monitoring of the reinforcement showed that the bars were highly polarized (around –900 mV) during the extraction, preventing the steel from returning to its usual potential values found in concrete structures.