Durability of mixtures containing calcium nitrite based corrosion inhibitor

Sideris, Kosmas K.; Savva, A.

doi:10.1016/j.cemconcomp.2004.02.016

Cited by 77 publications

(45 citation statements)

References 8 publications

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“…8,[12][13][14][15][16][17][18][19] Nitrite, being an oxidizing anodic inhibitor, oxidizes ferrous cations to ferric cations rapidly at anodic sites, which then precipitate out as ferric oxyhydroxides to repair defects in the passive film.…”

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confidence: 99%

Effect of Molybdate on the Passivation of Carbon Steel in Alkaline Solutions under Open-Circuit Conditions

Tan¹,

Wijesinghe

Blackwood

2016

J. Electrochem. Soc.

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The effect of molybdate on the passivation of AISI 1020 carbon steel under open-circuit conditions in pH 12.5 calcium hydroxide solutions containing chloride was investigated via electrochemical tests and surface characterization techniques. In the early stage, molybdate increased the rate of passivation, with inhibition efficiency being positive. During the later stage, after the carbon steel has passivated, precipitation of calcium molybdate over parts of the sample surface resulted in slight negative inhibition efficiency and the passive film was found to have a higher proportion of ferrous cations and a smaller thickness. However, the precipitation of a thick calcium molybdate film over the entire surface can reverse this situation, increasing the polarization resistance through a cathodic inhibition mechanism. The electrochemical and XPS results showed that regardless of its effect on the final polarization resistance, the presence of calcium molybdate precipitates led to a decrease in the total extent of carbon steel oxidation, indicating an overall beneficial effect. Molybdate was also shown to be effective against localized corrosion, with 14.6 mM molybdate sufficient in preventing passivity breakdown in pH 12.5 solution containing 564 mM chloride. Carbon steel is not a corrosion resistant alloy. However, in highly alkaline environments such as concrete, the formation of a passive oxide film on the surface reduces the corrosion rate to a very low level. 1In such environments, corrosion of carbon steel occurs mostly through two mechanisms: chloride contamination and carbonation by atmospheric CO 2 resulting in a pH drop.2-10 To counter the corrosion of carbon steel in highly alkaline environments, corrosion inhibitors can be added. Currently, calcium nitrite is being used in the construction industry as an admixed inhibitor for its set-accelerating and corrosion inhibition properties. 11Considerable research has been conducted on the inhibition of carbon steel corrosion in alkaline solutions by nitrite anions. 8,[12][13][14][15][16][17][18][19] Nitrite, being an oxidizing anodic inhibitor, oxidizes ferrous cations to ferric cations rapidly at anodic sites, which then precipitate out as ferric oxyhydroxides to repair defects in the passive film.11 Calcium nitrite works well for concrete with water to cement ratio less than 0.5 and the critical [ Despite its commercial use, concerns have been raised regarding the toxicity of calcium nitrite. 20,21 The oxidizing nature of nitrite that is essential for its corrosion inhibition effect leads to methemoglobin in humans, which is a reduction in the ability of red blood cells to transport oxygen due to Fe 2+ in hemoglobin being oxidized to Fe 3+ . This negative aspect of calcium nitrite is reflected in its being banned from use in immersed reinforced concrete structures due to toxicity and solubility issues.22 Therefore, despite calcium nitrite's commercial success as a concrete rebar inhibitor, there is an ongoing search for an alternative inhibitor for carbon st...

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mentioning

confidence: 99%

Effect of Molybdate on the Passivation of Carbon Steel in Alkaline Solutions under Open-Circuit Conditions

Tan¹,

Wijesinghe

Blackwood

2016

J. Electrochem. Soc.

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“…Corrosion inhibitors can be added to the fresh concrete for new structures or can be applied to the hardened concrete surface as surface applied inhibitors. Several studies have been conducted to evaluate the effectiveness of admixed inhibitors to inhibit the reinforcement corrosion in chloride enrich environment (Sideris et al 2005; Montes et al 2004;Saraswathy and Song 2007;Jamil et al 2003). These studies concentrate mainly on calcium nitrites, sodium nitrite, zinc oxide, ethanolamine based and amino-alcohol based inhibitors.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Impedance Spectroscopy to Study the Carbonation Behavior of Concrete Treated with Corrosion Inhibitors

Kaur

Goyal

Bhattacharjee

et al. 2017

ACT

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In this paper, electrochemical impedance spectroscopy was used as non destructive technique (NDT) for studying the carbonation behavior of the concrete sample treated with migratory type of organic corrosion inhibitors. Concrete carbonation was achieved in carbonation chamber by maintaining 5% CO 2 by volume, 60-70% relative humidity and 30 ± 2°C temperature for 90 days. The experimental results show that with progressive carbonation, porosity of the concrete reduces and results in denser microstructure. The concrete surface treated with corrosion inhibitor C.I. 1 (amine -ether based) and C.I. 2 (2-aminobenzoic acid) shows the behaviour different form the control sample at the end of exposure conditions. Impedance results indicate that carbonation depth can be predicted by analyzing the high frequency arc of Nyquist plot. Also, both of the tested inhibitors were able to form a passive layer around the rebar surface and their efficiencies improved with time.

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“…No caso particular do concreto, essas substâncias devem ser ativas em um meio alcalino e não devem alterar substancialmente suas propriedades físicas, químicas e mecânicas (ANDRADE, 1992;FREIRE, 2005;GENTIL, 1996;MEDEIROS et al, 2002). Um inibidor de corrosão ideal pode ser definido como um componente químico que, quando adicionado ao concreto em quantidades adequadas, pode retardar a corrosão da armadura de aço e não tem efeitos contrários às suas propriedades (HANSSON et al, 1998;SIDERIS;SAVVA, 2005).…”

Section: Introductionunclassified

Inibidores De Corrosão Do Concreto: Estudo Prospectivo

Lima-Coelho¹,

Neto²,

Silva³

et al. 2015

CPROSP

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RESUMOAs peças de concreto armado e estruturas metálicas tem apresentado uso crescente em aplicações residenciais e comerciais dadas as possibilidades de uso e as qualidades destes materiais, mas o concreto está sempre sujeito a sofrer com a corrosão. No caso da armadura de aço em concreto, a corrosão é sempre um processo destrutivo de natureza eletroquímica. Torna-se imprescindível a otimização de forma a reduzir a corrosão, aumentando o tempo de vida e segurança das obras que utilizam estes elementos. Esta pesquisa visa demonstrar a relevância do tema em estudo por meio da quantificação de estudos realizados, não só de cunho tecnológico, mas também científico e do levantamento das patentes depositadas nos últimos 10 anos, relacionadas aos inibidores de corrosão do concreto, identificando os países ou estados que tem se destacado nestes estudos. A pesquisa aponta China e Estados Unidos como os países com maior número de patentes depositadas. Contudo, há muito a ser explorado e uma grande diversidade de produtos que ainda podem ser desenvolvidos, considerando as particularidades de cada região.Palavras chave: Concreto. Inibidor de Corrosão. Patentes. ABSTRACTThe reinforced concrete and steel structures are very useful in construction of commercial and residential building, and its use is growing fast, but the concrete is generally susceptible to suffer with corrosion. In the case of steel reinforcement in concrete, corrosion is always a destructive process of electrochemical nature that claims for solutions in order to prevent accidents and give long life to the buildings. This study aims to demonstrate the relevance of the topic under study by mapping the research done on this area , not only of technological nature, but also scientific and survey of patents over the last 10 years related to concrete corrosion inhibitors, identifying countries or regions that have been highlighted in these studies. Our search indicates China and the United States as the countries with the largest number of patents. However, there is much more to be explored and a wide variety of products that can still be developed, take in account the particular character of use in each region.

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Durability of mixtures containing calcium nitrite based corrosion inhibitor

Cited by 77 publications

References 8 publications

Effect of Molybdate on the Passivation of Carbon Steel in Alkaline Solutions under Open-Circuit Conditions

Effect of Molybdate on the Passivation of Carbon Steel in Alkaline Solutions under Open-Circuit Conditions

Electrochemical Impedance Spectroscopy to Study the Carbonation Behavior of Concrete Treated with Corrosion Inhibitors

Inibidores De Corrosão Do Concreto: Estudo Prospectivo

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