Corrosion-Inhibiting Systems for Durable Concrete Bridges. II: Accelerated Laboratory Investigation

Abstract

Nine commercially available corrosion-inhibiting systems for use in concrete structures exposed to corrosive environments were evaluated on bridge barrier walls and in electrochemical cells. The results of this study are presented in two companion papers reporting on a five-year field evaluation and an accelerated laboratory investigation. The latter, presented in this paper, included the assessment of the effect of the corrosion inhibitors on the oxidation and reduction reactions by the cyclic voltammetry method, and their effectiveness in delaying or reducing corrosion by measurements of chloride thresholds and corrosion rates. The results indicated that the inorganic admixture and some organic admixtures performed very well in the saturated calcium hydroxide solution (pH of 12.6); however, their performance improvement over the control was not observed in a simulated concrete pore solution (pH of 13.5). Although tests in simulated concrete pore solutions cannot adequately simulate all the complex conditions usually found in the field, they were very useful to rapidly identify the effects of the corrosion inhibitors on the corrosion reactions, and to provide supporting information to the corresponding field evaluation.