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Journal of Chemistry
Volume 2015 (2015), Article ID 521507, 10 pages
http://dx.doi.org/10.1155/2015/521507
Research Article

Effect of Organic Inhibitors on Chloride Corrosion of Steel Rebars in Alkaline Pore Solution

Department of Engineering and Applied Sciences, INSTM RU Bergamo and University of Bergamo, Viale Marconi 5, 24044 Dalmine, Italy

Received 21 November 2014; Revised 21 January 2015; Accepted 22 January 2015

Academic Editor: Sebastijan Peljhan

Copyright © 2015 Marina Cabrini et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The inhibition properties of aspartic and lactic acid salts are compared with nitrite ions with regard to their effect on critical chloride concentration. The tests were carried out on carbon steel specimens in simulated pore solutions with initial pH in the range of 12.6 to 13.8. The critical chloride concentrations were estimated through multiple specimen potentiostatic tests at potentials in the usual range for passive rebar in noncarbonated concrete structures. During tests, chloride ions were progressively added until all specimens showed localized attack, obtaining cumulative distribution curves reporting the fraction of corroded specimens as a function of chloride concentration. The presence of the organic inhibitors on the passivity film was detected by IR spectra. The results confirm that 0.1 M aspartate exhibits an inhibiting effect comparable with nitrite ions of the same concentration. Calcium lactate does not increase critical chloride concentration; however it appears to promote the formation of a massive scale, reducing the corrosion propagation.