Bidirectional electromigration of a corrosion inhibitor in chloride contaminated concrete

Abstract

Triethylenetetramine (TETA), as a corrosion inhibitor for steel in aqueous media, was introduced into chloride-contaminated concrete, specimens by using a novel method called bidirectional electromigration rehabilitation (BIEM). An electric field was applied between embedded steel cathodes and external anodes to inject the corrosion inhibitor from external electrolytes into the concrete, and at the same time to extract the chloride ions from the concrete cover zone. In part 1, after the treatment, the specimens were drilled to determine the concentration profiles of the corrosion inhibitor, chloride and hydroxyl ions within the concrete. The effects of variations in the applied current density, duration of electrolysis, water/cement ratio, initial chloride content and surface carbonation on the concentration profiles of the proposed ions were determined. Electrochemical chloride extraction (ECE), in which saturated calcium hydroxide solution was used as an external electrolyte, was applied in control experiments. As expected, chloride content decreased and alkalinity increased after the treatment. Also, the concentration of the inhibitor injected around the embedded steel bars was adequate to provide corrosion protection. The results can provide a direction in designing the BIEM process.