5-year chemico-physical evolution of concrete–claystone interfaces, Mont Terri rock laboratory (Switzerland)

Mäder, Urs; Jenni, Andreas; Lerouge, Cathérine; Gaboreau, Stephane; Miyoshi, Satoru; Kimura, Yukinobu; Cloet, Veerle; Fukaya, Masaaki; Claret, Francis; Otake, Tsubasa; Shibata, Masahito; Lothenbach, Babara (2017). 5-year chemico-physical evolution of concrete–claystone interfaces, Mont Terri rock laboratory (Switzerland). Swiss journal of geosciences, 110(1), pp. 307-327. Springer 10.1007/s00015-016-0240-5

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The Cement–Opalinus Clay Interaction (CI) Experiment at the Mont Terri rock laboratory is a long-term passive diffusion–reaction experiment between contrasting materials of relevance to engineered barrier systems/near-field for deep disposal of radioactive waste in claystone (Opalinus Clay). Reaction zones at interfaces of Opalinus Clay with two different types of concrete (OPC and “low-pH”/ESDRED) were examined by sampling after 2.2 and 4.9 years. Analytical methods included element mapping (SEM, EPMA), select spot analysis (EDAX), 14C-MMA impregnation for radiography, and powder methods (IR, XRD, clay-exchanger characterisation) on carefully extracted miniature samples (mm). The presence of aggregate grains in concrete made the application of all methods difficult. Common features are a very limited extent of reaction within claystone, and a distinct and regularly zoned reaction zone within the cement matrix that is more extensive in the low-alkali cement (ESDRED). Both interfaces feature a de-calcification zone and overprinted a carbonate alteration zone thought to be mainly responsible for the observed porosity reduction. While OPC shows a distinct sulphate enrichment zone (indicative of ingress from Opalinus Clay), ESDRED displays a wide Mg-enriched zone, also with claystone pore-water as a source. A conclusion is that substitution of OPC by low-alkali cementitious products is not advantageous or necessary solely for the purpose of minimizing the extent of reaction between claystone and cementitious materials. Implications for reactive transport modelling are discussed.

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:

Mäder, Urs and Jenni, Andreas

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

1661-8726

Publisher:

Springer

Language:

English

Submitter:

Andreas Jenni

Date Deposited:

27 Apr 2017 15:15

Last Modified:

27 Apr 2017 15:15

Publisher DOI:

10.1007/s00015-016-0240-5

BORIS DOI:

10.7892/boris.96087

URI:

https://boris.unibe.ch/id/eprint/96087

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