Local electrochemistry of reinforcement steel – Distribution of open circuit and pitting potentials on steels with different surface condition

Stefanoni, Matteo; Angst, Ueli; Elsener, Bernhard

doi:10.1016/j.corsci.2015.06.004

Cited by 41 publications

(25 citation statements)

References 18 publications

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“…200 mV, immersion in an alkaline solution reduced this inhomogeneity to ca. 20 mV within one day (measured after removal from solution) [29]. This indicates relatively fast transformation, i.e.…”

Section: Native Rust Layersmentioning

confidence: 89%

“…Stefanoni et al [29] measured local open circuit potentials of individual points on the surface of ''asreceived'' reinforcement steels by locally contacting the steel with a test electrolyte and an electrochemical sensor. Surfaces with only black mill-scale or rebars that were severely pre-rusted (entire surface covered with rust) showed a narrow distribution of local open circuit potentials (standard deviation ca.…”

Section: Native Rust Layersmentioning

confidence: 99%

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The steel–concrete interface

et al. 2017

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Although the steel-concrete interface (SCI) is widely recognized to influence the durability of reinforced concrete, a systematic overview and detailed documentation of the various aspects of the SCI are lacking. In this paper, we compiled a comprehensive list of possible local characteristics at the SCI and reviewed available information regarding their properties as well as their occurrence in engineering structures and in the laboratory. Given the complexity of the SCI, we suggested a systematic approach to describe it in terms of local characteristics and their physical and chemical properties. It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. The SCI can differ strongly between different engineering structures and also between different members within a structure; particular differences are expected between structures built before and after the 1970/1980s. A single SCI representing all on-site conditions does not exist. Additionally, SCIs in common laboratory-made specimens exhibit significant differences compared to engineering structures. Thus, results from laboratory studies and from practical experience should be applied to engineering structures with caution. Finally, recommendations for further research are made. This report was prepared by the working group within RILEM TC 262-SCI, and further reviewed and approved by all members of the RILEM TC 262-SCI.

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Section: Native Rust Layersmentioning

confidence: 89%

Section: Native Rust Layersmentioning

confidence: 99%

The steel–concrete interface

et al. 2017

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“…It is believed that the Fe 2+ /Fe 3+ couple present on the steel surface strongly dominated the potential of the rebars. It has been reported that rusted steel has a 10 times higher cathodic oxygen reduction current compared to steel with mill scale [29]. This was explained by the fact that the sites for oxygen reduction are reduced by -FeOOH crystals -the more rust is available to be reduced the more intense is the cathodic oxygen reduction [30].…”

Section: Experiences Madementioning

confidence: 99%

Experiences from RILEM TC 235-CTC in recommending a test method for chloride threshold values in concrete

et al. 2018

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Chloride threshold value is an important input parameter in service life predictions. There has been a need for a reliable method for testing this value in order to improve the understanding of basic factors influencing the corrosion initiation. For this reason RILEM technical committee (TC) 235-CTC was formed with the ultimate aim to recommend a suitable test method capable of delivering data with acceptable measurement uncertainty. During the TC’s life, a test method was proposed and a Round-Robin Test (RRT) was organised to evaluate it. Due to the unexpected results from the RRT, the ultimate aim of the TC was not reached. There were some experiences obtained from the TC’s work especially in designing the test method which are worthy for supporting future researchers continuing to search for a reliable test method for it. This technical letter presents the TC’s experiences.

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“…6) may be explained by properties of both the steel and the concrete. A current study presented at this conference [8] using local electrochemical measurements [9] has revealed large differences in electrochemical properties of the steel surface between locations on or between ribs. Local concrete properties may also be influenced by the rebar geometry for instance regions of plastic settlement below a rib (vertical rebars), which, similar to the bleedwater zone below horizontal bars [10][11][12][13], may promote corrosion initiation [14].…”

Section: Steel Surfacementioning

confidence: 99%

Towards understanding corrosion initiation in concrete – influence of local concrete properties in the steel-concrete interfacial zone

2018

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Chloride-induced corrosion is the most common deterioration process for reinforced infrastructure objects. Improving the understanding of the conditions for initiation of localized corrosion is urgently needed. Research is focused on the influence of “defects” at the steel-concrete interface (SCI), as these weak points might be responsible for corrosion initiation. In contrast to numerous studies with “lab concrete”, this study reports results from reinforced concrete cores drilled from old infrastructure objects containing a non-corroding rebar. In contrast to laboratory studies, this guarantees real conditions at the SCI comprising also irregularities such as air voids, plastic settlement voids, cracks, etc. This allows to study chloride-induced corrosion in real conditions and to determine the so-called “critical chloride content” Ccrit. Visual inspection of the SCI enables to establish (or not) influences of the local conditions at the SCI and Ccrit. It was found that Ccrit strongly decreased with the carbonation depth, even if the carbonation front had not reached the steel. Moreover, coarse air voids and cracks were in this study not particularly susceptible sites for corrosion initiation.

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Local electrochemistry of reinforcement steel – Distribution of open circuit and pitting potentials on steels with different surface condition

Cited by 41 publications

References 18 publications

The steel–concrete interface

The steel–concrete interface

Experiences from RILEM TC 235-CTC in recommending a test method for chloride threshold values in concrete

Towards understanding corrosion initiation in concrete – influence of local concrete properties in the steel-concrete interfacial zone

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