Alteration of Bentonite Reacted with Cementitious Materials for 5 and 10 Years in the Mont Terri Rock Laboratory (CI Experiment)

Yokoyama, Shingo; Shimbashi, Misato; Minato, Daisuke; Watanabe, Yasutaka; Jenni, Andreas; Mäder, Urs (2021). Alteration of Bentonite Reacted with Cementitious Materials for 5 and 10 Years in the Mont Terri Rock Laboratory (CI Experiment). Minerals, 11(3), p. 251. MDPI 10.3390/min11030251

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The cement–clay interaction (CI) experiment was carried out at the Mont Terri rock laboratory to complement the current knowledge on the influence that cementitious materials have on Opalinus Clay (OPA) and bentonite (MX). Drill cores including the interface of OPA, concrete (LAC = low-alkali binder, and OPC = ordinary Portland cement), and MX, which interacted for 4.9 and 10 years, were successfully retrieved after drilling, and detailed analyses were performed to evaluate potential mineralogical changes. The saturated compacted bentonites in core samples were divided into ten slices, profiling bentonite in the direction towards the interface, to evaluate the extent and spatial variation of the mineralogical alteration of bentonite. Regarding the mineral compositions of bentonite, cristobalite was dissolved within a range of 10 mm from the interface in both LAC-MX and OPC-MX, while calcite precipitated near the interface for OPC-MX. In LAC-MX and OPC-MX, secondary products containing Mg (e.g., M-S-H) also precipitated within 20 mm of the interface. These alterations of bentonite developed during the first 4.9 years, with very limited progress observed for the subsequent 5 years. Detectable changes in the mineralogical nature of montmorillonite (i.e., the formation of illite or beidellite, increase in layer charge) did not occur during the 10 years of interaction.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Rock-Water Interaction

UniBE Contributor:

Jenni, Andreas and Mäder, Urs

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

2075-163X

Publisher:

MDPI

Language:

English

Submitter:

Andreas Jenni

Date Deposited:

01 Mar 2021 15:16

Last Modified:

07 Mar 2021 03:13

Publisher DOI:

10.3390/min11030251

Uncontrolled Keywords:

cement–clay interaction bentonite cementitious materials alteration alkaline conditions

BORIS DOI:

10.48350/152761

URI:

https://boris.unibe.ch/id/eprint/152761

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