Bentonite/CEM-II cement mortar INTERFACE EXPERIMENTS: A proxy to in situ deep geological repository engineered barrier system surface reactivity

González-Santamaría, Daniel E.; Fernández, Raúl; Ruiz, A.; Ortega, A.; Cuevas, Jaime

doi:10.1016/j.apgeochem.2020.104599

Cited by 6 publications

(1 citation statement)

References 47 publications

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“…Many studies on the mineralogical alteration of bentonite, as described above, have been carried out based on a high liquid-solid ratio used in powder samples. In contrast, there are a number of uncertainties that must be considered as the mineralogical alteration of compacted bentonite materials under alkaline conditions has not been extensively investigated [14][15][16][17][18][19]. Long-term alteration of bentonite materials in radioactive waste disposal is predicted by numerical analysis, such as in reactive transport modelling.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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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.

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