Effect of Nitrite Ions on Steel Corrosion Induced by Chloride or Sulfate Ions

Popoola

International Journal of Corrosion

2018

This paper studies behaviours of Cymbopogon citratus leaf-extract and NaNO 2 , used as equal-mass admixture models, in 3.5% NaCl-immersed steel-reinforced concrete by nondestructive electrochemical methods and by compressive-strength improvement/reduction effects. Corrosion-rate, corrosion-current, and corrosion-potential constitute electrochemical test-techniques while compressive-strength effect investigations followed ASTM C29 and ASTM C33, in experiments using positive-controls for the electrochemical and compressive-strength studies. Analyses of the different electrochemical test-results mostly portrayed agreements on reinforcing-steel anticorrosion effects by the concentrations of natural plant and of chemical admixtures in the saline/marine simulating-environment and in the distilled H 2 O (electrochemical positive control) of steel-reinforced concrete immersions. These indicated that little amount (0.0833% cement for concrete-mixing) of Cymbopogon citratus leaf-extract was required for optimal inhibition efficiency, = 99.35%, on reinforcing-steel corrosion, in the study. Results of compressive-strength change factor also indicated that the 0.0833% Cymbopogon citratus concentration outperformed NaNO 2 admixture concentrations also in compressive-strength improvement effects on the NaCl-immersed steel-reinforced concrete. These established implications, from the study, on the suitability of the eco-friendly Cymbopogon citratus leaf-extract for replacing the also highly effective NaNO 2 inhibitor of steel-in-concrete corrosion in concrete designed for the saline/marine service-environment.

Section: Statistical Analyses and Test Of Fitting Significancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Popoola

International Journal of Corrosion

2018

“…So in the early stage of filling nitrite solution into the holes of mortar, the mole ratio of nitrite to chloride was very low and the rate of nitrite ions to inhibit corrosion was much lower than the rate of chloride ions to accelerate corrosion. However, due to the gradual accumulation of nitrite in pore solution, the mole ratio of nitrite to chloride would gradually increase, which led to the increase of the rate of nitrite to passivate the steel and the decrease of the rate of chloride to dissolve the steel [17]. So in the later stage of filling nitrite solution into the holes of mortar, with the increasing of mole ratio of nitrite to chloride, the corrosion of anode would be inhibited and led to the increase of half-cell potential of anode and the decrease of corrosion current density.…”

Section: Time Evolution Curves Of Half-cell Potential and Corrosion Cmentioning

confidence: 99%

“…In simulated concrete pore solution, nitrite was found to be effective in inhibiting pit initiation [15] and pit propagation [16]. Chloride threshold level was not only increased with the increasing of nitrite concentration but also affected by pH [17]. The inhibiting efficiency of nitrite decreased when the pH was reduced [18].…”

Section: Introductionmentioning

confidence: 96%

“…In neutral and acid solutions simulating the electrolytic environments of micropores of concrete in the propagation period, any addition of nitrite cannot effectively reduce the corrosion level [19]. Highly alkaline environment plays an important role in assisting nitrite to inhibit corrosion [17]. However, the study done by Mammoliti et al [20] in synthetic alkaline pore solution indicated that nitrite ions were unsuccessful in increasing the chloride threshold level of steel exposed to chloride and had a minimal effect on corrosion rate once corrosion was initiated.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Nitrite Inhibitor on the Macrocell Corrosion Behavior of Reinforcing Steel

Cao

Hibino

Goda

2015

Journal of Chemistry

Self Cite

The effect of nitrite ions on the macrocell corrosion behavior of reinforcing steel embedded in cement mortar was investigated by comparing and analyzing the macrocell corrosion current, macrocell polarization ratios, and slopes of anodic and cathodic steels. Based on the experimental results, the relationship between macrocell potential difference and macrocell current density was analyzed, and the mechanism of macrocell corrosion affected by nitrite ions was proposed. The results indicated that nitrite ions had significant impact on the macrocell polarization ratios of cathode and anode. The presence of nitrite could reduce the macrocell current by decreasing the macrocell potential difference and increasing the macrocell polarization resistance of the anode.

A Review on Corrosion in Concrete Structure: Inhibiting Admixtures and Their Compatibility in Concrete

et al. 2021

The development in marine industry and its effort in building bridges has placed a huge demand on reliability and duration of service of reinforcing steel in concrete. Literature has documented several studies on corrosion of reinforcing steel in concrete induced via carbonation and chloride in marine milieus. Extension of concrete structures service life has been one of the foremost strong worries of the concrete industry, especially for marine industry. Hence, the necessity to employ a cost effect system for shielding the reinforced steel in concrete from corrosion. Studies have shown that one prospective solution in combating corrosion deterioration in reinforced steel in concrete structures is the introduction of corrosion-inhibiting admixtures into concrete. This review discussed at length corrosion in reinforced concrete and corrosion inhibitors in relation to concrete together with the classification of inhibitors based on the method of applications. This review further reports corrosion-inhibiting admixtures in concrete. As a result, the aspects of corrosion inhibitors this manuscript reviewed are corrosion inhibitors employed as admixtures in concrete for new construction in the marine industry. Furthermore, corrosion inhibitors are employed for repairs and maintenances admixed with concrete for patches on marine structures, squirted onto the surface of the concrete or put on the concrete surface via saturation treatment. As a result of the excellent properties of functional nanostructured materials, the advancement in the implementation of functional materials in inhibiting admixtures in concrete is fast growing in marine industry. Hence, the Integration of functional materials in inhibiting admixture and their compatibility were reviewed. The significance of inhibitors employed as admixtures in concrete for practical applications of corrosion are the suppression or mitigation of corrosion process of metals used in marine industry and the patches of already constructed structures. The current problems related to corrosion-inhibiting admixtures in concrete and the future research and development directions were discussed.