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A minisandwich experiment with blended ca-bentonite and pearson water—Hydration, swelling, solute transport and cation exchange

Emmerich, Katja 1; Bakker, Eleanor 1; Königer, Franz; Rölke, Christopher; Popp, Till; Häußer, Sarah; Diedel, Ralf; Schuhmann, Rainer 1
1 Kompetenzzentrum für Materialfeuchte (CMM), Karlsruher Institut für Technologie (KIT)


Shaft seals are geotechnical barriers in nuclear waste deposits and underground mines. The Sandwich sealing system consists of alternating sealing segments (DS) of bentonite and equipotential segments (ES). MiniSandwich experiments were performed with blended Ca-bentonite (90 mm diameter and 125 mm height) to study hydration, swelling, solute transport and cation exchange during hydration with A3 Pearson water, which resembles pore water of Opalinus Clay Formation at sandy facies. Two experiments were run in parallel with DS installed either in one-layer hydrate state (1W) or in air-dry two-layer hydrate (2W) state. Breakthrough at 0.3 MPa injection pressure occurred after 20 days and the fluid inlet was closed after 543 days, where 4289 mL and 2984 mL, respectively, passed both cells. Final hydraulic permeability was 2.0–2.7 × 10$^{-17}$ m$^{2}$. Cells were kept for another 142 days before dismantling. Swelling of DS resulted in slight compaction of ES. No changes in the mineralogy of the DS and ES material despite precipitated halite and sulfates occurred. Overall cation exchange capacity of the DS does not change, maintaining an overall value of 72 ± 2 cmol(+)/kg. ... mehr

Verlagsausgabe §
DOI: 10.5445/IR/1000138659
Veröffentlicht am 06.10.2021
DOI: 10.3390/min11101061
Zitationen: 1
Web of Science
Zitationen: 1
Zitationen: 1
Cover der Publikation
Zugehörige Institution(en) am KIT Kompetenzzentrum für Materialfeuchte (CMM)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2021
Sprache Englisch
Identifikator ISSN: 2075-163X
KITopen-ID: 1000138659
Erschienen in Minerals
Verlag MDPI
Band 11
Heft 10
Seiten Art. Nr.: 1061
Bemerkung zur Veröffentlichung Gefördert durch den KIT-Publikationsfonds
Vorab online veröffentlicht am 28.09.2021
Schlagwörter anion distribution; CEC; exchangeable cations; hydration; MiniSandwich; sandwich sealing system; solute transport; swelling pressure
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