The homogenisation behaviour of BCV bentonite - A laboratory and numerical study

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11310%2F23%3A10476920" target="_blank" >RIV/00216208:11310/23:10476920 - isvavai.cz</a>

Alternative codes found

RIV/68407700:21110/23:00366340

Result on the web

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=GXFTbESpsn" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=GXFTbESpsn</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.clay.2023.106969" target="_blank" >10.1016/j.clay.2023.106969</a>

Result language

angličtina

Original language name

The homogenisation behaviour of BCV bentonite - A laboratory and numerical study

Original language description

Bentonite is considered as a suitable sealing material for radioactive waste geological repositories because of its high swelling capacity and low permeability. Regardless of the construction procedure and initial form of the bentonite, i.e. blocks, pellets, powder or combinations and mixtures thereof, the placement of the bentonite barrier results in initial heterogeneities which could potentially form preferential pathways for the migration of radionuclides. This study focused on the laboratory investigation of the homogenisation of Czech BCV bentonite. The analysis comprised the performance of four sets of tests on dual-density samples composed of two layers of bentonite compacted to various dry densities. Each set of tests considered two identical samples saturated from different sides under constant volume conditions. Homogenisation was investigated through the measurement of swelling pressure on both sides of the samples and via the determination of the final density distribution in a vertical profile from the post-mortem analysis. The results confirmed a substantial degree of homogenisation, with only a small density gradient revealed by the post-mortem analysis. The density distribution profiles indicated a gradual change in the vertical direction with no distinct border between the original layers. A higher degree of homogenisation was found in the samples with a higher overall density and, consequently, a higher swelling potential. No clear effect of the direction of saturation on homogenisation was identified from the density profiles. The final swelling pressures corresponded well to swelling pressures obtained on single-density samples with density equal to the global density of the dual-density samples. The numerical modelling repre-sented well the final swelling pressures and the swelling pressure evolution curves for both the single-and dual -density samples (including the distinct experimentally-observed swelling pressure peak when the dual-density sample was saturated from the high-density end). More accurate results were obtained while considering the porosity and the degree of saturation-dependent permeability. However, the model did not fully capture the homogenisation of the dual-density samples in terms of the dry density profiles. While the tendency towards homogenisation was predicted correctly, two distinct density zones were evident in the simulations, while the experiment revealed a gradual density distribution.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10505 - Geology

Project

—

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2023

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Applied Clay Science

ISSN

0169-1317

e-ISSN

1872-9053

Volume of the periodical

241

Issue of the periodical within the volume

September

Country of publishing house

NL - THE KINGDOM OF THE NETHERLANDS

Number of pages

9

Pages from-to

106969

UT code for WoS article

001002051800001

EID of the result in the Scopus database

2-s2.0-85159374881