Experimental characterization of cement–bentonite interaction using core infiltration techniques and 4D computed tomography

Dolder, Florian; Mäder, Urs; Jenni, Andreas; Schwendener, Nicole (2014). Experimental characterization of cement–bentonite interaction using core infiltration techniques and 4D computed tomography. Physics and chemistry of the earth, 70-71, pp. 104-113. Elsevier 10.1016/j.pce.2013.11.002

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Deep geological storage of radioactive waste foresees cementitious materials as reinforcement of tunnels and as backfill. Bentonite is proposed to enclose spent fuel drums, and as drift seals. The emplacement of cementitious material next to clay material generates an enormous chemical gradient in pore water composition that drives diffusive solute transport. Laboratory studies and reactive transport modeling predict significant mineral alteration at and near interfaces, mainly resulting in a decrease of porosity in bentonite. The goal of this project is to characterize and quantify the cement/bentonite skin effects spatially and temporally in laboratory experiments. A newly developed mobile X-ray transparent core infiltration device was used, which allows performing X-ray computed tomography (CT) periodically without interrupting a running experiment. A pre-saturated cylindrical MX-80 bentonite sample (1920 kg/m3 average wet density) is subjected to a confining pressure as a constant total pressure boundary condition. The infiltration of a hyperalkaline (pH 13.4), artificial OPC (ordinary Portland cement) pore water into the bentonite plug alters the mineral assemblage over time as an advancing reaction front. The related changes in X-ray attenuation values are related to changes in phase densities, porosity and local bulk density and are tracked over time periodically by non-destructive CT scans.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Service Sector > Institute of Legal Medicine > Forensic Medicine
08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Rock-Water Interaction

UniBE Contributor:

Dolder, Florian Dominik; Mäder, Urs; Jenni, Andreas and Schwendener, Nicole

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

1474-7065

Publisher:

Elsevier

Language:

English

Submitter:

Florian Dominik Dolder

Date Deposited:

17 Jan 2014 11:03

Last Modified:

03 Aug 2017 09:21

Publisher DOI:

10.1016/j.pce.2013.11.002

BORIS DOI:

10.7892/boris.40021

URI:

https://boris.unibe.ch/id/eprint/40021

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