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

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.

Application of Plants Extracts as Green Corrosion Inhibitors for Steel in Concrete - A review

“…Several researchers proposed mechanism of steel corrosion in concrete (Shahid, 2011;Jae et al, 2016;Cabrini et al, 2015;Elsener, 2001;Söylev, 2008;Ormellese et al, 2006;Page, 1975;Hausmann, 1967;Gouda, 1970;Valcarce, 2008;Freire, et al, 2009;Cabrini, 2002;Asma et al, 2011). All agree that corrosion on rebar is influenced by properties of concretes.…”

Cymbopogon citratusand NaNO2Behaviours in 3.5% NaCl-Immersed Steel-Reinforced Concrete: Implications for Eco-Friendly Corrosion Inhibitor Applications for Steel in Concrete

“…The least performance by the NaNO 2 admixture concentrations employed was by the 0.3333% NaNO 2 having = 87.73%. Studies have documented that nitrite exhibits this highly effective corrosion performance on steel-rebar due to its ability to form chloride ion-blocking protective film on the reinforcing-steel, in cooperation with the hydroxyl ion [28,34]. This form of passive layer could be less porous and more compact such that it could shift the corrosion-potential towards more electropositive direction while it mitigates corrosion effects in chloride-contaminated environment [34].…”

“…Among these techniques, the use of corrosion inhibitors attracts much preference due to its economically lower cost, labour saving, and ease of applications, all combined with its relative effectiveness at mitigating corrosion of steel embedded in concrete [20,[26][27][28][29][30]. Applications of corrosion inhibitors can take the form of admixture into freshly cast concrete or it can be applied unto the surface of already cast concrete structures as migratory corrosion inhibitors (MCIs) [31][32][33].…”

“…The problem with corrosion inhibiting admixture usage depends on the fact that admixture substances that have been known to be effective in inhibiting chloride-induced reinforcing-steel corrosion in concrete include compounds of nitrites and of chromates [26,28,30,35,36]. The challenges from using these substances are that they are environmentally hazardous due to their toxicity and lethality to living beings/organs, even as they also exhibit ability to cause hereditarily inheritable health conditions [15,[37][38][39].…”

Corrosion Inhibitors for Reinforced Concrete: A Review

“…It creates a hydrophobic layer that helps to repel moisture away from the steel rebar [67]. Monticelli et al [68] investigated the different type of inhibitors based on amine/alkanol amine and carboxylate (dicarboxylic and hydrocarboxylic acids) on steel corrosion behavior in saturated calcium hydroxide solution containing 0.1 M chloride and chloride admixed mortar.…”