A1 Journal article (refereed)
A method for measuring wetting and swelling of bentonite using X-ray imaging (2022)

Harjupatana, T., Miettinen, A., & Kataja, M. (2022). A method for measuring wetting and swelling of bentonite using X-ray imaging. Applied Clay Science, 221, Article 106485. https://doi.org/10.1016/j.clay.2022.106485

JYU authors or editors

Publication details

All authors or editors: Harjupatana, Tero; Miettinen, Arttu; Kataja, Markku

Journal or series: Applied Clay Science

ISSN: 0169-1317

eISSN: 1872-9053

Publication year: 2022

Volume: 221

Article number: 106485

Publisher: Elsevier

Publication country: Netherlands

Publication language: English

DOI: https://doi.org/10.1016/j.clay.2022.106485

Publication open access: Openly available

Publication channel open access: Partially open access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/80380

Abstract

A non-invasive method based on X-ray imaging for measuring deformation and water transport in wetting and swelling bentonite samples is introduced. Sequential X-ray images taken of the samples were used to calculate the attenuation coefficient and deformation. These results, together with careful calibration, allowed finding the dry density and water content distributions and their temporal evolution in the wetting and swelling samples. A specific correction technique, based on regularly taking reference X-ray images of aluminum plates of varying thickness, was developed and used to take into account X-ray beam instabilities and thus to improve the accuracy of density analysis. Large deformation, present in the experiments, was measured with an improved version of a block-matching algorithm. The X-ray imaging method was used here to measure the axial swelling of compacted MX-80 bentonite samples in a tube when in contact with saline solution (0.1 M NaCl). This setup mimics a scenario where bentonite, planned to be used as a buffer material in a nuclear waste repository placed deep in the bedrock, swells into a rock fracture filled by groundwater. The method yielded potentially valuable data on hydro-mechanical behavior of bentonite, which may be used in developing and validating material models to be used in safety assessment of nuclear waste repository concepts.

Keywords: clay; bentonite; water; water content; advection; x-ray examination; tomography

Free keywords: X-ray imaging; Deformation; Swelling

Contributing organizations

Ministry reporting: Yes

Reporting Year: 2022

JUFO rating: 1