Reaction kinetics of FEBEX bentonite in hyperalkaline conditions resembling the cement–bentonite interface

Experimental study of the effect of pH on the kinetics of montmorillonite dissolution at 25°C

“…While we did not directly observe brucite formation, the conditions suggest a potential partial precipitation of Mg as brucite or other Mg-rich minerals (e.g., saponite) (Sánchez et al, 2006).…”

“…Heydemann, 1966;Novak and Č ičel, 1978;Kline and Fogler, 1981a,b;Furrer et al, 1993;Zysset and Schindler, 1996;Bauer and Berger, 1998;Cama et al, 2000;Huertas et al, 2001;Tournassat et al, 2003;Nakayama et al, 2004;Amram and Ganor, 2005;Choi et al, 2005a,b;Metz et al, 2005a,b;Sánchez et al, 2006;Golubev et al, 2006) that have considered dissolution-affecting processes including: formation of surface complexes, evolution of reactive surface area, effects of solution saturation, and rate control by steady state vs. initial dissolution reaction(s). The results are in some cases discrepant as they were obtained under different experimental conditions (batch or flowthrough reactors, far or close to equilibrium conditions), using different smectites (in addition to raw or pretreated, 0016-7037/$ -see front matter Ó 2008 Elsevier Ltd. All rights reserved.…”

Nature of C-(A)-S-H Phases Formed in the Reaction Bentonite/Portlandite

“…Experimental evidence demonstrates that the impact of the alkaline plume on bentonite will generate partial dissolution of montmorillonite, formation of illite/smectite mixed layers [8,9], precipitation of Na/K-zeolites and trioctahedral Mg smectite [4,10,11] under hyperalkaline conditions (pH > 12.5), and formation of calcium silicates hydrates (C-S-H) and Mg-clays [3,12] under alkaline conditions (pH < 12.5). The nature of the products largely depends on the experimental conditions, including temperature, pH, clays and solution compositions, and duration of the reaction [13].…”

“…For laboratory experiments, usually cement mortar is used instead of concrete. The cement/bentonite interactions, and more generically, cement/clay interactions, have been studied by laboratory experiments, either at low water/solid ratios in advective transport cells, using compacted bentonite and cement mortar probes [1,2], or at high water/solid ratios, studying mineral reactions in batch reactors [3,4]. In addition, geochemical models have been used to explain the results or pursuing the extrapolation of mineral reactivity in the long term [5][6][7].…”

Swelling pressure and hydraulic conductivity of compacted GMZ01 bentonite under salinization–desalinization cycle conditions

“…For such barrier, the swelling pressure of compacted bentonite makes it possible to maintain the stability of the repository structure, and the low permeability makes it possible to restrict the transfer of radionuclide released from the waste packages after possible failure of canister. In the underground repository, there are certain chemical composition in the pore water of compacted bentonite and surrounding rock Sanchez et al, 2006;Hueckel and Hu, 2009). Meanwhile, some mineral substance will be gradually dissolved from compacted bentonite, surrounding rock, or concrete facility to the pore water in the process of long-term interaction between themselves (Fernandez et al, 2009).…”