Influences of Electric Potential and Electrolyte on Electrochemical Chloride Removal in Reinforced Concrete

Yodsudjai, Wanchai; Saelim, W.

doi:10.1061/(asce)mt.1943-5533.0000777

Cited by 14 publications

(7 citation statements)

References 12 publications

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“…Liu and Shi (2012) conducted a numerical investigation to examine the effect of various factors (external current density, treatment time, initial chloride content, rebar position, coarse aggregates and cracks) on the efficiency of removing chlorides from heterogeneous concrete materials. Yodsudjai and Saelim (2014) conducted a laboratory investigation of ECE on concrete specimens with a water-to-cement ratio of 0.45 and found that 76 per cent of chloride content could be removed at 2 cm depth from concrete surface, after a 28-day, 15-V treatment using saturated Ca(OH) 2 solution as the external electrolyte. In a study by the Minnesota Department of Transportation in 1999, although the ECE process reduced chloride levels in the treated structures by approximately 50 per cent, several locations in the structures following ECE still had chloride concentrations in excess of the chloride threshold level (Chauvin et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…It was found that the ECE treatment halted chloride-induced pitting in concrete specimens that were under attack, but increased the overall corrosion rate of the rebar. ECE can also alter the chemistry and morphology of the cement paste, especially near the steel-concrete interface, leading to Na-rich, Ca-Al-rich, Fe-rich or Ca-rich crystals and an alkali-silica-rich gel at the interface (Liu and Shi, 2012;Yodsudjai and Saelim, 2014) and in samples with a higher number of pores with a smaller pore size in the concrete (Fajardo and Escadeillas, 2006). More studies can be found in a review conducted by Liu and Shi (2009).…”

Section: Introductionmentioning

confidence: 99%

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Effect of electrochemical chloride extraction treatment on the corrosion of steel rebar in chloride contaminated mortar

Nguyen

et al. 2016

ACMM

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Purpose This work aims to demonstrate the use of electrochemical chloride extraction (ECE) to remove chloride ions away from the steel rebar in chloride-contaminated mortar and to mitigate the corrosion of the embedded steel. Design/methodology/approach To simulate salt contamination in concrete, sodium chloride was added at 0.5 per cent by weight of cement in the fresh mortar featuring a water-to-cement ratio of 0.45. The ECE treatments were varied at two electrical current densities (1 and 5 A/m2), using two electrolytes (0.1M NaOH and 0.1M Na3BO3 solutions) and for two periods (2 and 4 weeks). The average free chloride concentration in cement mortars before and after ECE treatment was quantified using a customized chloride sensor, whereas the spatial distribution of relevant elements was obtained using energy-dispersive X-ray spectroscopy. The effect of ECE treatment on the electric resistivity of mortar and the corrosion resistance of steel rebar was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization measurements, respectively. Findings The experimental results reveal that the ECE treatment was effective in removing chlorides and in improving electric resistivity and compressive strength of the mortar, when using the sodium borate solution as the electrolyte. In this case, a 4-week ECE treatment at 1 A/m2 decreased the free chloride content in the mortar by 70 per cent, significantly increased the Ca/Si ratio in the mortar near rebar, led to a more refined and less permeable microstructure of the mortar and significantly improved its compressive strength. The ECE treatment was able to halt the chloride-induced corrosion of steel rebar by passivation. A 4-week ECE treatment at 1 A/m2 using sodium hydroxide and sodium borate solutions decreased the corrosion rate of rebar by 36 and 34 per cent, respectively. Originality/value This electrochemical rehabilitation of steel-reinforced concrete under chloride-contaminated condition is very effective in prolonging its service life.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of electrochemical chloride extraction treatment on the corrosion of steel rebar in chloride contaminated mortar

Nguyen

et al. 2016

ACMM

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“…Therefore, the use of pulsed current is presented in the literature as an alternative method to minimize those problems in the particular case of cathodic protection systems [6,7]. However, no references have been found in the literature on the use of pulsed current for studying chloride transport in chloride extraction and/or realkalinisation related problems, were DC current is widely employed [8][9][10], although a number of important unwanted side effects have been reported [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Chloride transport through cementitious membranes using pulsed current

Díaz¹,

Nóvoa²,

Puga³

et al. 2013

Cement and Concrete Composites

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Microstructural changes and chloride transport in cement pastes are studied under DC current and pulsed electric fields. Impedance Spectroscopy and Ultrasonic Pulse Velocity measurements have been employed for quasi-real time monitoring of changes in the cement paste microstructure. The results show that the electric resistivity and ultrasound velocity (measured at 500 kHz) are modified during the migration experiments. At the end of test, Mercury Intrusion Porosimetry reveals an important increase in the fraction of gel pores. The experimental results show conduction enhanced through gel pores. The use of pulsed current is presented as an alternative method to minimize the negative effects produced by DC current.

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“…Liu and Shi [18] conducted a numerical investigation to examine the effect of various factors (external current density, treatment time, initial chloride content, rebar position, coarse aggregates, and cracks) on the efficiency of removing chlorides from heterogeneous concrete materials. Yodsudjai and Saelim [19] conducted a laboratory investigation of ECE on concrete specimens with a water-to-cement ratio of 0.45 and found that "76% of chloride content could be removed … at 2 cm depth from concrete surface", after a 28-day, 15-Volt treatment using saturated lime solution as the external electrolyte.…”

mentioning

confidence: 99%

Electrochemical Chloride Extraction and Inhibitor Injection in Salt-Contaminated Repair Mortar

Gong¹,

Shen²,

Tong³

et al. 2017

Preprint

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Repair mortar is commonly used to rehabilitate reinforced concrete structures or components that exhibit a relatively high level of distresses. Yet, this repair mortar can be contaminated by salt from its service environment. This work employs a two-dimensional finite element model to investigate the transport behavior of ionic species in salt-contaminated and water-saturated repair mortar under an externally applied electric field. The model was experimentally validated and then utilized to evaluate the effectiveness of electrochemical chloride extraction (ECE) with or without electrical injection of corrosion inhibitor (EICI). In the case study, both the ECE alone and the ECE+EICI treatment was found effective in decontaminating the zone in front of the steel rebar. In both techniques, the magnitude of current density has a significant effect on removing chloride out of the mortar and increasing the pH of the pore solution near the rebar, whereas the treatment time any not have a significant effect under some scenarios. The injection of the organic corrosion inhibitor significantly slowed down the removal of chloride. Changes in the ionic distribution in the mortar were generally beneficial in reducing the corrosion risk of the steel rebar and thus extending the service life of the repair mortar.

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Influences of Electric Potential and Electrolyte on Electrochemical Chloride Removal in Reinforced Concrete

Cited by 14 publications

References 12 publications

Effect of electrochemical chloride extraction treatment on the corrosion of steel rebar in chloride contaminated mortar

Effect of electrochemical chloride extraction treatment on the corrosion of steel rebar in chloride contaminated mortar

Chloride transport through cementitious membranes using pulsed current

Electrochemical Chloride Extraction and Inhibitor Injection in Salt-Contaminated Repair Mortar

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