Quantification of Water Content Across a Cement-clay Interface Using High Resolution Neutron Radiography

Shafizadeh, Amir; Gimmi, Thomas; Loon, Luc R. Van; Kaestner, Anders; Lehmann, Eberhard; Maeder, U.; Churakov, Sergey V.

doi:10.1016/j.phpro.2015.07.073

Cited by 13 publications

(18 citation statements)

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“…In the last decades, there has been a growing interest to use pore-scale modelling in combination with experimental imaging/characterisation of porous media as tools to get a better understanding of coupled chemical and transport processes and to upscale the results to a macroscopic representation 2,[14][15][16][17] . A live monitoring of chemical processes and hydraulic pathways can be performed using non invasive techniques such as magnetic res-onance imaging 18 , positron emission tomography 19 , or neutron imaging 20 . The spatial resolution, however, is often a limiting factor for these techniques.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic flow-through reactor and 3D Raman imaging forin situassessment of mineral reactivity in porous and fractured porous media

et al. 2020

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Section: Introductionmentioning

confidence: 99%

Microfluidic flow-through reactor and 3D Raman imaging forin situassessment of mineral reactivity in porous and fractured porous media

et al. 2020

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“…Unfortunately, no porosity measurements are possibly during in-situ experiments. A new method based on neutron imaging of small laboratory samples (Shafizadeh et al, 2015) may provide additional experimental data in the future.…”

Section: Introductionmentioning

confidence: 99%

Interaction of ordinary Portland cement and Opalinus Clay: Dual porosity modelling compared to experimental data

Jenni

Gimmi

Alt‐Epping

et al. 2017

Physics and Chemistry of the Earth, Parts A/B/C

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Interactions between concrete and clays are driven by the strong chemical gradients in pore water and involve mineral reactions in both materials. In the context of a radioactive waste repository, these reactions may influence safetyrelevant clay properties such as swelling pressure, permeability or radionuclide retention. Interfaces between ordinary Portland cement and Opalinus Clay show weaker, but more extensive chemical disturbance compared to a contact between low-pH cement and Opalinus Clay. As a consequence of chemical reactions porosity changes occur at cement-clay interfaces. These changes are stronger and may lead to complete pore clogging in the case of low-pH cements. The prediction of pore clogging by reactive transport simulations is very sensitive to the magnitude of diffusive solute fluxes, cement clinker chemistry, and phase reaction kinetics. For instance, the consideration of anion-depleted porosity in clays substantially influences overall diffusion and pore clogging at interfaces. A new concept of dual porosity modelling approximating Donnan equilibrium is developed and applied to an ordinary Portland cement-Opalinus Clay interface. The model predictions are compared with data from the cement-clay interaction (CI) field experiment in the Mt Terri underground rock laboratory (Switzerland), which represent 5 y of interaction. The main observations such as the decalcification of the cement at the interface, the Mg enrichment in the clay detached from the interface, and the S enrichment in the cement detached from the interface, are qualitatively predicted by the new model approach. The model results reveal multiple coupled processes that create the observed features. The quantitative agreement of modelled and measured data can be improved if uncertainties of key input parameters (tortuosities, reaction kinetics, especially of clay minerals) can be reduced.

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“…Experimental investigations on the cement-clay interfaces often use composite specimens consisting of cement/mortar/concrete and compacted clay (Sugiyama and Tsuji 2008;Dauzeres et al 2010;Shafizadeh et al 2015;Fernández et al 2016;Yamaguchi et al 2016;Balmer et al 2017) same as the first paper. More recently, long-term in-situ experiments in underground research laboratories (URL) on the cement-clay interfaces have also been conducted (Read et al 2001;Gaboreau et al 2012;Mäder et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Calcite Precipitation at Cement–Bentonite Interface. Part 2: Acceleration of Transport by an Electrical Gradient

Nakarai

Watanabe

Koibuchi³

et al. 2021

ACT

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Calcium leaching from cementitious materials in contact with bentonite in nuclear waste repositories can alter the functionality of an engineered barrier system. In this study, we contribute to the fundamental understanding of calcite precipitation at cement-bentonite interfaces by adding carbonate to bentonite. In addition, we accelerate the transport of charged reactants towards the interface using an electrochemical migration method. The carbonate admixture successfully promotes calcite precipitation at the surface of cement paste. The analysis also revealed that the amount of precipitated calcite is not simply correlated to the amount of added carbonate or the applied electrical potential. Experiments in which bentonite pore water contains high initial contents of carbonate exhibit rapid calcite precipitation in a very narrow region at the cement-bentonite interface, resulting in pore clogging.

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Quantification of Water Content Across a Cement-clay Interface Using High Resolution Neutron Radiography

Cited by 13 publications

References 10 publications

Microfluidic flow-through reactor and 3D Raman imaging forin situassessment of mineral reactivity in porous and fractured porous media

Microfluidic flow-through reactor and 3D Raman imaging forin situassessment of mineral reactivity in porous and fractured porous media

Interaction of ordinary Portland cement and Opalinus Clay: Dual porosity modelling compared to experimental data

Calcite Precipitation at Cement–Bentonite Interface. Part 2: Acceleration of Transport by an Electrical Gradient

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