Evaluation of corrosion inhibitors in synthetic concrete pore solutions.

摘要

Chloride-induced corrosion is responsible for the deterioration of many reinforced concrete structures such as roads, bridges, parking garages, and marine structures. The increased use of deicing salts in particular has escalated the severity and financial repercusions of this phenomenon.; The use of chemical inhibitors as admixtures in concrete is a fairly recent method of preventing chloride-induced corrosion. The most attention to date has been given to those inhibitors which are nitrite-based, particularly calcium nitrite (Ca(NO{dollar}sb2)sb2).{dollar} However, this market is quickly expanding and many organic and other inorganic compounds are being introduced.; Full cyclic potentiostatic polarization, linear polarization and pH measurements were employed to determine the effectiveness of four commercially available inhibitors in synthetic concrete pore solution. X-ray photoelectron spectroscopy was utilized to examine the nature of the passive film formed on rebar samples exposed to solutions containing a nitrite inhibitor and that without inhibitor. Samples were also microscopically examined for evidence of pitting corrosion. Through this regime of tests, it was also possible to determined if the proposed inhibiting mechanisms involved depletion of the inhibitor.; All inhibitors were found to be ineffective, regardless of aeration state, relative to results obtained in the control solution. In some cases, the presence of an inhibitor had a deleterious effect on the corrosion behaviour of the immersed rebar samples. An alternate inhibiting mechanism for calcium nitrite was also postulated. No consumption of any of the inhibitors was observed.; A concurrent study was also performed to determine the relative importance of the surface finish and type of electrolyte used. Surface topography was found to significantly affect chloride threshold values. The composition of the electrolyte also affected the chloride threshold value, pitting tendencies and repassivation behaviour. (Shortened by UMI.)