Investigations of an ethanolamine‐based corrosion inhibitor system for surface treatment of reinforced concrete

Abstract

Laboratory investigations were performed to assess the efficacy of a proprietary ethanolamine-based corrosion inhibitor system when applied to the surface of reinforced concrete specimens that were chloride-contaminated to varying extents in the presence or absence of carbonation. The corrosion responses of embedded steel bars at various depths of cover were monitored electrochemically during a controlled programme of cyclic wetting and drying undertaken for several months prior to the inhibitor treatment and for approximately eighteen months thereafter. Gravimetric measurements of the quantities and distribution of corrosion on the steel were also made on completion of the exposure tests. Analysis of aqueous extracts from treated concrete revealed that the ethanolamine component of the inhibitor system penetrated to depths of more than 15 mm within the concrete. It was found that, for inhibitor-treated specimens, there was some reduction in the corrosion rate of pre-corroding steel at low cover depths in non-carbonated concrete with modest levels of chloride contamination. At higher levels of chloride contamination and in carbonated specimens, however, the ethanolamine-based inhibitor was apparently ineffective under the conditions investigated.

Electrochemical inhibitor injection for control of reinforcement corrosion in carbonated concrete

“…6 and this is in accord with previous findings for steel bars embedded in carbonated concrete without added chloride [18].…”

“…After the bars had been abraded very lightly with emery paper to remove loosely adherent fragments of concrete, taking care not to damage the steel surfaces, they were visually examined. The exposed central regions of the bars (away from their epoxy-masked ends) were then cut into eight equal segments, each with a length of 10 mm, using the precision wire erosion method with a wire diameter of 200 mm [16,18]. The eight 10 mm segments of steel that were thus obtained from each bar were cleaned in 10% diammonium hydrogen citrate solution with 150 ppm 2-mercaptobenzothiazole as corrosion inhibitor in order to remove the corrosion products and any residual concrete debris without significantly damaging the underlying steel, as recommended elsewhere [19].…”

Ion chromatographic analysis of amines, alkanolamines, and associated anions in concrete

“…Three types of sample containing inhibitor ions were examined by means of ion chromatography: (a) solutions obtained by water extraction of powdered samples taken from different depths within concrete or cement paste specimens [14,16,17]; (b) pore liquid expressed from cement paste as described elsewhere [18,19]; and (c) solutions containing standard cations and spiked with inhibitor ions.…”

Electrochemical and analytical characterization of three corrosion inhibitors of steel in simulated concrete pore solutions

“…Unfortunately, admixed corrosion inhibitors may affect the process of cement hydration, morphology, and microstructure of hardened cementitious materials (pore structures, Cl -transport, and C−S−H gel structure) [1]. However, migrating corrosion inhibitors also have the difficulty in penetrating the steel surface through the concrete [2]. Moreover, their efficiency is restrained to some extent by the initial chloride concentration [3].…”