Non-saturated ion diffusion in concrete – A new approach to evaluate conductivity measurements

Olsson, Nilla; Baroghel-Bouny, Véronique; Nilsson, Lars-Olof; Thiéry, Mickaël

doi:10.1016/j.cemconcomp.2013.04.001

Cited by 56 publications

(41 citation statements)

References 26 publications

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“…The published results with respect to the relationship between chloride diffusion coefficient and moisture content show a large scatter [6]. The role of water-to-cement (w/c) ratio in the non-saturated chloride diffusion is still a point of controversy in view of the existing research works [7,13,17]. The moisture distribution in the pore structure and its effect on the non-saturated chloride diffusion are not clear.…”

Section: Introductionmentioning

confidence: 97%

“…7 for a comparative analysis. Based on the Nernst-Einstein equation and conductivity technique, Olsson et al [13] determined the D rc -S w relations in the cement mortars with w/c ratios of 0.38 and 0.53. Between the study of Olsson et al and this study, the data are not very different for high saturation S w levels, whereas disagreements arise for low saturation levels.…”

Section: R 0 -Values At Various Saturationsmentioning

confidence: 99%

“…For ''RH'' preconditioning, the sample (often saturated) is dried step-by-step under drier humidity circumstances until the sample is in equilibrium to the target humidity level, i.e. water loss \ 0.02 g/week [13]. The different humidity circumstances can be controlled by saturated salt solutions [18].…”

Section: Sample Preconditioning For Desired Moisture Contentmentioning

confidence: 99%

“…It is worthwhile to note that imposing the different chloride sources into unsaturated concretes may lead to unwanted moisture redistribution and/or microstructural alteration in the concretes. The conductivity technique, combined with the Nernst-Einstein equation, is an alternative approach to determine the chloride diffusion coefficient in the non-saturated cementitious materials [11][12][13][14][15][16]. Compared to direct diffusion tests, conductivity measurements are fast and easy to perform.…”

Section: Introductionmentioning

confidence: 99%

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Influence of moisture condition on chloride diffusion in partially saturated ordinary Portland cement mortar

Zhang

2018

Mater Struct

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Experiments have been carried out to study the influence of moisture condition, including moisture content and its distribution, on the chloride diffusion in partially saturated ordinary Portland cement mortar. The mortar samples with water-tocement (w/c) ratios of 0.4, 0.5 and 0.6, cured for 1 year, were preconditioned to uniform water saturations ranging from 18 to 100%. The interior relative humidities of these partially saturated cement mortars, i.e. water vapour desorption isotherm (WVDI), were measured. The WVDI results in relation to the pore structures obtained from the mercury intrusion porosimetry tests of paste samples with the same w/ c ratios were analyzed, which provided a basic insight into the moisture distribution in the non-saturated cement mortars. The relative chloride diffusion coefficients of cement mortars at various water saturations were determined based on the Nernst-Einstein equation and conductivity technique. It is found that the relative chloride diffusion coefficient D rc depends on the degree of water saturation S w and WVDI. At a given S w level, the D rc is larger for a higher w/c ratio. The role of the w/c ratio in the D rc -S w relation, however, becomes less pronounced with increasing w/ c ratio. There exists a critical saturation, below which the water-filled capillary pores are discontinuous and the D rc -value tends towards infinitely small. An increase of the w/c ratio results in a decrease of the critical saturation level.

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Section: Introductionmentioning

confidence: 97%

Section: R 0 -Values At Various Saturationsmentioning

confidence: 99%

Section: Sample Preconditioning For Desired Moisture Contentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of moisture condition on chloride diffusion in partially saturated ordinary Portland cement mortar

Zhang

2018

Mater Struct

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“…The overall speed of chloride ingress as reflected by D APP , when "averaged" over these two periods therefore became similar for saturated and non-saturated specimens. As models are being designed to predict chloride ingress in unsaturated concrete materials subject to both ionic concentration gradient and moisture gradient (Ehlen et al, 2009;Olsson, Baroghel-Bouny, Nilsson, & Thiery, 2013;Samson & Marchand, 2007), the fact that air voids (10-500 mm) are not as easily filled as most capillary pores (10 nm to 10 mm) should be considered, as this directly alters the determination of chloride content at each depth, and thus, the time of corrosion initiation. The reduced chloride diffusion coefficients when air voids are empty should also be investigated and accounted for.…”

Section: Non-steady-state Migration Testsmentioning

confidence: 99%

Saturation of Air Entrained Voids and Its Implication on the Transport of Ionic Species in Concrete

Bu¹,

Weiss²

2014

Proceedings of the 4th International Conference on the Durability of Concrete Structures

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Air entrainment is commonly used to improve the durability of concrete materials exposed to freezing and thawing. While the influence of air voids on freeze/thaw damage and salt scaling is frequently studied, the influence of entrained air voids on ionic transport has been studied less frequently. Since ionic transport in concrete materials relies on pore fluid as the medium of conduction, only saturated or partially saturated air voids participate in the transport processes. This paper discusses the conditions under which air voids could become saturated. Specifically, the saturation condition of entrained air voids in laboratory tests and in service is discussed. This paper compares the results of steady and non-steady state migration tests on concrete specimens when air voids are saturated and when air voids are primarily empty. The implications of the observed difference are discussed to provide a better understanding of the direct application of laboratory test results to predict the service life of concrete materials in the field. The saturation of air voids is observed to also influence the electrical resistivity of concrete materials.

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Modeling the Long‐term Stability of Multi‐barrier Systems for Nuclear Waste Disposal in Geological Clay Formations

Claret

Marty

Tournassat

2018

Reactive Transport Modeling

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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Non-saturated ion diffusion in concrete – A new approach to evaluate conductivity measurements

Cited by 56 publications

References 26 publications

Influence of moisture condition on chloride diffusion in partially saturated ordinary Portland cement mortar

Influence of moisture condition on chloride diffusion in partially saturated ordinary Portland cement mortar

Saturation of Air Entrained Voids and Its Implication on the Transport of Ionic Species in Concrete

Modeling the Long‐term Stability of Multi‐barrier Systems for Nuclear Waste Disposal in Geological Clay Formations

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