Corrosion inhibitors for reinforced concrete structures: a study of binary mixtures

• A. Brenna, F. Bolzoni, MP. Pedeferri and M. Ormellese

Politecnico di Milano, Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta”, Via Mancinelli 7, 20131 Milano, Italia

Abstract: Corrosion inhibitors are used to prevent or delay corrosion of steel reinforcement in concrete. Available commercial products are of inorganic nature based on sodium nitrite (acknowledged to be the most effective product), or organic mixtures based on amines, alkanolamines, fatty acids and carboxylic substances. During the last 15 years in our laboratories an intense experimental research aimed at identifying new organic substances or mixtures thereof that might have greater inhibiting effectiveness on corrosion by chlorides. This paper present the results of electrochemical tests carried out in alkaline solution, in the presence of chlorides, that were conducted on binary mixtures made with three substances (nitrite, DMEA and benzoate). Electrochemical tests (namely potentiodynamic and potentiostatic polarisation) were carried out. Some of the mixtures exhibited a marked synergistic effect in the potentiodynamic polarisation tests, with a clear-cut increase in the pitting potential. In potentiostatic polarisation the effect on the critical chloride concentration for the initiation of localised corrosion were limited.

Keywords: rebar corrosion, chlorides, inhibitors, critical chloride content, mixtures, pitting potential, potentiostatic polarisation.

Int. J. Corros. Scale Inhib., 2017, 6, no. 1, 59–69 PDF (1 249 K)
doi: 10.17675/2305-6894-2017-6-1-5

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