An equivalent electrical circuit of macrocell activity in facing electrodes embedded in cement mortar

Keddam, M.; Nóvoa, X.R.; Soler, L.; Andrade, Carmen; Takenouti, H.

doi:10.1016/0010-938x(94)90140-6

Cited by 21 publications

(16 citation statements)

References 7 publications

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“…3 Hence, the proposed relatively simplified equivalent circuit is believed to be satisfactory for evaluation of the system parameters, where the components have clear physical meaning. This consideration is supported by the values obtained from the fitting procedures ͑Table I͒, which correspond well to values reported in similar research 3,7,31,[52][53][54] and are evidenced by an acceptable error ͑see Fig. 9͒.…”

Section: Journal Of the Electrochemical Society 154 ͑3͒ E45-e56 ͑200supporting

confidence: 87%

Electrochemical Behavior, Microstructural Analysis, and Morphological Observations in Reinforced Mortar Subjected to Chloride Ingress

Koleva¹,

Breugel²,

Wit³

et al. 2007

J. Electrochem. Soc.

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The behavior of steel reinforcement was studied using electrochemical impedance spectroscopy ͑EIS͒ and polarization resistance ͑PR͒ techniques in conditions of chloride-induced corrosion in ordinary Portland cement-mortar specimens immersed in 7% NaCl for a test period of 120 days and compared to specimens immersed in demineralized water for the same period as reference specimens. This study was an initial phase of ongoing research on electrochemical methods for corrosion protection in reinforced concrete structures and aimed at investigating the applicability of widely accepted techniques as EIS and PR and their possible correlation with structural observations of the bulk matrix, relevant to cement-based materials science and product-layers distribution, to corrosion and further protection. The results indicate that the concept of EIS modeling and the components used in the latter correspond well to alterations in structural properties of the bulk matrix, while the electrochemical behavior can be additionally supported by morphological observations of the steel/cement paste interface. As is well known, corrosion in reinforced concrete is a great concern with respect to structure durability. Corrosion in concrete can take place when carbon dioxide has penetrated to the steel surface or when chloride content in the vicinity of the steel bars reaches certain threshold values.1 Consequently, breakdown of the passive layer, normally deposited on the steel surface in the concrete alkaline medium, is taking place. The assessment of the condition of reinforced structures in terms of time to initiate reinforcement corrosion, the level of damage, the performance of the system related to mechanical properties, evaluation of efficiency of protection techniques, etc. is always related to estimating corrosion rates, i.e., to determination of electrochemical parameters for the steel reinforcement in certain technical and environmental conditions. The electrochemical behavior of steel reinforcement has been extensively studied and outcomes are reported in literature. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] The intention of this work is to see how well different electrochemical techniques agree for reinforced cement-based materials rather than obtaining absolute quantitative parameters ͑such as corrosion rate for example͒ and, further, to correlate results with structural and morphological observations of the bulk matrix and the steel/cement paste interface, thus setting up a combination of techniques for the assessment of corrosion and protection in reinforced concrete. Applicability of Electrochemical Techniques to Reinforced Cement-Based MaterialsDifferent approaches hold for the performance of electrochemical ͑EC͒ measurements and their applicability to reinforced concrete, including possible errors in measuring the related corrosion parameters. 7,13,[16][17][18][19][20] A recent study 21 presents comprehensive information on the application of EC techniques in investigating the corrosion of steel reinforcemen...

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Section: Journal Of the Electrochemical Society 154 ͑3͒ E45-e56 ͑200supporting

confidence: 87%

Electrochemical Behavior, Microstructural Analysis, and Morphological Observations in Reinforced Mortar Subjected to Chloride Ingress

Koleva¹,

Breugel²,

Wit³

et al. 2007

J. Electrochem. Soc.

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“…These values are not compatible with an interthcial film [16]. According to some works [17,18], this order of magnitude is indicative of bulk effects and the high frequency process is related to the dielectric properties of concrete cover [ 19,20].…”

Section: Tests On Reinforced Concretementioning

confidence: 82%

Studies on corrosion inhibition of steel reinforcement by phosphate and nitrite

et al. 2003

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This work deals with the effectiveness of sodium phosphates and nitrites used as inhibitors against steel corrosion in concrete reinforcement. First, concrete pore water was simulated with several alkaline solutions. Then, reinforced concrete specimens with inhibitors added in fresh concrete mix are immersed in chloride solution. The effectiveness of inhibitors was assessed by applying electroclaemical techniques, namely Eleclrochemical hnpedance Spectroscopy (E[S), Polafisation Curves (PC), and Open Circuit Potential (OCP) measurements. The final concrete condition was analysed with Scanning Electronic Microscopy (SEM), X-Ray Diffraction (XRD) and infrared Spectroscopy (FT-IR).In solutions simulating concrete contaminated with chloride, the influence of the it~aibitors on the steel corrosion was assessed by (PC) and (EIS). The results obtained show that phosphate prevents pitting corrosion when its content is equal to chloride concentration, and that nitrite only contributes to inc~ease the value of pitting potential. Corrosion rate is reduced with both inhibitors at the different contents tested.For reinforced concrete specimens immersed in chloride solution, theft conditions were assessed by applying EIS. The results indicate that after 1 year of immersion with the two inhibitors the corrosion rate decreased. Then, aIter 3 years of immersion no influence ofinhibitors on the corrosion rate was observed. However a significant increase in concrete electrical resistance was obsewed when inhibitors were present. Visual examinations showed that all steel bars were corroded in the presence of chlorides.Results from analytical tests done on the concrete after 3 years of irranersion show that as far as the final concrete condition is concerned, the test~ inhibitors did not change the type of compounds in concrete. But the final fi'ee Chloride content remained higher than the critical chloride tN~shold. The results of FT-IR technique showed that nitrites are likely washed out of concrete during immersion in chloride solution and phosphates interfere with the equilibrium between CO3 2 and HCO3" in concrete.The main conclusion of this study is: the efficiency of the tested inhibitors decreases with time, after two years of immersion in chloride solution. I~SUMI~ ffi'aetion des rayons" X (DRX) et la Spectroscopie Infi~arouge (IR). En milieu simulant le b~ton contamin~ par les chlorures, l'influence de l'inhibiteur sur la corrosion a ~t~ dvalu~e par (CP) et (SIE), Les r~sultats ~ obtenus ont montr~ que les pho~phat~ I N T R O D U C T I O NThe application of corrosion inhibitor is a technique for preventing steel corrosion in concrete exposed to chloride environments. Several papers have been published on the effectiveness of inhibitors mixed in fresh concrete [1][2][3][4][5][6]. This paper is a complement to previous works [7][8][9], which have shown the inhibiting effect of sodium phosphate and sodium nitrite tested in simulated concrete solutions.The efficiency of these two inhibitors was assessed by using steel...

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“…tance also have been determined. [44][45] Generally, active reinforcements seem to exhibit greater values of C than passive reinforcements. 44 The values of R p in concrete that are carbonated or contaminated with chlorides can be located around 10,000 Ω-cm 2 , confi rmed by repeated gravimetric testing, 46-51 whereas much larger values, ≥100,000 Ω-cm 2 , often in the vicinity of 1,000,000 Ω-cm 2 , are typical of passive reinforcements.…”

Section: Reasons To Use a Randles Ec Instead Of More Complicated Modelsmentioning

confidence: 95%

Electrochemical Techniques for Studying Corrosion of Reinforcing Steel: Limitations and Advantages

González¹,

Miranda²,

Birbilis³

et al. 2005

CORROSION

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This paper presents a comparison of the results obtained by different electrochemical techniques when applied to passive and active steel embedded in mortar or in simulated pore water solutions. The techniques investigated include polarization resistance by means of current or potential steps, potentiodynamic tests at different polarization rates, the application of potentiostatic and galvanostatic pulses, and electrochemical impedance spectroscopy (EIS). The differences between the corrosion current density (i corr ) values obtained using different techniques, or by applying the same technique in different conditions, are predicted by theory, and are often greater than an order of magnitude. Many of these errors, particularly in passive systems, are a result of incorrect application of the electrochemical techniques, rather than the techniques themselves being inadequate for probing the behavior of the steel/ concrete system. When electrochemical techniques are used correctly, they can provide fast, quantitative, and trustworthy data, although not precisely exact, regarding the corrosion rate of steel in concrete.

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An equivalent electrical circuit of macrocell activity in facing electrodes embedded in cement mortar

Cited by 21 publications

References 7 publications

Electrochemical Behavior, Microstructural Analysis, and Morphological Observations in Reinforced Mortar Subjected to Chloride Ingress

Electrochemical Behavior, Microstructural Analysis, and Morphological Observations in Reinforced Mortar Subjected to Chloride Ingress

Studies on corrosion inhibition of steel reinforcement by phosphate and nitrite

Electrochemical Techniques for Studying Corrosion of Reinforcing Steel: Limitations and Advantages

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