Electrochemical chloride extraction: Efficiency and impact on concrete containing 1% of NaCl

Souza, Luan. Rodrigo de Almeida; Medeiros, Marcelo Henrique Farias de; Pereira, Eduardo; Capraro, Ana Paula Brandão

doi:10.1016/j.conbuildmat.2017.04.010

Cited by 30 publications

(7 citation statements)

References 23 publications

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“…It has been reported that ECE efficiency can be affected by many factors, such as current density, water/binder (w/b) ratio, electrolyte type. It was found that the amounts of removed chlorides increased with the applied current density, water/binder ratio and treatment time and 40-55% of the total chlorides can be removed from concrete within a relatively short period [12,16,17]. To further improve the ECE efficiency, some researchers introduced SiO3 2into anolyte [18] and increased operation temperatures [19].…”

Section: Ohmentioning

confidence: 99%

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Efficiency of electrochemical extraction of chlorides in fly ash concrete using carbon fibre mesh anode

et al. 2020

Construction and Building Materials

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This paper presents an experimental study on the effect of anode format (carbon fibre sheet (Cs), mesh (Cm) and plate (Cp)), current density (0, 1, 2, and 3 A/m 2 referred to the surface area of reinforcement), and fly ash content (plain concrete, 10%, 20% and 30% replacement by weight of cement) on the efficiency of electrochemical chloride extraction (ECE). The results showed the total extracted chloride contents of samples treated with different anodes had an order of Cs > Cm > Cp. The distribution of anodic reaction products indicated that only a small part of Cs played as anode because of the insulation in its transverse direction while Cm performed better conductivity uniformity and accordingly higher usage. With the increase of current density, the extracted chloride content improved, but the improvement was very limited when the current density kept rising. The incorporation of fly ash led to 12% ~ 153.1% improvement in extracted chlorides. After ECE, the measured residual free chloride content in concrete did not change with current density or fly ash content, except for the cases when current density was increased from 0 to 1 A/m 2 . The additional extracted chlorides with increasing current density or fly ash content can be attributed to the dissolution of bound chlorides. The contribution of increasing compactness by adding fly ash was offset by the destruction of Friedel's salt and the resulting release of chloride ions in the alkali environment and under the impressed currents.

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Section: Ohmentioning

confidence: 99%

“…Two electrochemical protection methods, cathodic protection (CP) and electrochemical chloride extraction (ECE), are appropriate and effective for chloride-contaminated reinforced concrete structures [7][8][9][10]. During ECE treatment, the chemical reactions that occurred at the anode can be expressed as follows [11,12]:…”

Section: Introductionmentioning

confidence: 99%

Efficiency of electrochemical extraction of chlorides in fly ash concrete using carbon fibre mesh anode

et al. 2020

Construction and Building Materials

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“…Tests on potential and resistivity of concrete cover [ 25 ] are employed in evaluating the growth of reinforcement corrosion in concrete. Quantitative assessment of the corrosion rate using polarization methods (LPR, GP and EIS) is performed more seldom [ 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Imperial Smelting Process Slag Addition in Self Compacting Concrete Concrete on the Efficiency of Electrochemical Chloride Extraction

et al. 2023

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This paper presents the analysis of how ISP slag addition affects the effectiveness of chloride extraction from self-compacting concrete. Corrosion processes were initiated by chloride ions added to concrete by the method accelerated with an electric field. Corrosion of reinforcement was monitored using the method of linear polarization resistance (LPR). Polarization measurements of steel reinforcement and chloride profiles were analysed to evaluate the effectiveness of electrochemical extraction. Microstructural analysis was conducted on a specimen of concrete after migration and extraction of chlorides. The presence of chloride ions and the application of an electric field during migration were tested with respect to the changed microstructure of concrete evaluated on the basis of image analysis using a scanning electron microscope (SEM). The research contributes to a better understanding of the corrosion processes caused by the presence of chloride ions in concretes in which ISP slag was used as a substitute for sand in various amounts. Thanks to the treatments of concrete with already corroding reinforcement bars, it can be concluded that the moderate replacement of sand with ISP slag limited to 25% allows for the effective inhibition of corrosion processes taking place in these concretes. However, it is not possible to completely withdraw already started corrosion processes in steel. The observations of the microstructure of concrete in which sand was completely replaced with ISP slag indicate that after prolonged use of the chloride extraction process, we can expect a change in the microstructure and the formation of ettringite, which may cause the concrete structure to burst. The obtained information will contribute to the development of modelling methods for chloride ion extraction from a wide range of currently used concretes.

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“…To date, various research works have focused on the question of electrochemical chloride extraction (ECE) [4][5][6]. In these studies, simulations have also been used in order to investigate the effect of chloride movement through concrete; however, in comparison with this work, major differences exist [7][8][9]-firstly, for electrochemical chloride extraction, much higher voltages are common and lower voltage ranges are not usually examined.…”

Section: Introductionmentioning

confidence: 99%

Analytical and Numerical Investigation of an Electrochemical Chloride Barrier for Reinforced Concrete Structures

Drießen-Ohlenforst¹,

Raupach²

2021

Materials

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During the development of a carbon-reinforced mortar interlayer for bridges, the idea of an electrochemical chloride barrier arose. An electrical field is generated between two carbon meshes, and the negatively charged chloride ions are held on the polarized upper carbon mesh to prevent chloride-induced corrosion in the reinforcement. Laboratory tests unexpectedly showed that higher voltages lead to an increase in chloride ions for certain depths of the reference probes. This paper discusses the implementation of analytical and numerical models that finally explain the effect only by the acting diffusion and migration with the help of a finite differences model and finite elements simulations. The effect of the local minimum is limited to positions above the depth of the first carbon layer of the test specimens. It is caused by the lines of the electrical field between the first and second carbon layer. According to the experimental and finite elements simulation results, higher voltages lead to lower chloride concentrations for all positions below the first carbon layer only after sufficient time duration. Therefore, the intended effect of an electrochemical chloride barrier can in general only be observed and confirmed after a certain time depending on position, conditions and parameters.

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Electrochemical chloride extraction: Efficiency and impact on concrete containing 1% of NaCl

Cited by 30 publications

References 23 publications

Efficiency of electrochemical extraction of chlorides in fly ash concrete using carbon fibre mesh anode

Efficiency of electrochemical extraction of chlorides in fly ash concrete using carbon fibre mesh anode

Effect of Imperial Smelting Process Slag Addition in Self Compacting Concrete Concrete on the Efficiency of Electrochemical Chloride Extraction

Analytical and Numerical Investigation of an Electrochemical Chloride Barrier for Reinforced Concrete Structures

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