TY - JOUR
T1 - Cation Filtration of Montmorillonite on Hydraulic Conductivities of Some Bentonites in Artificial Seawater
AU - Komine, Hideo
N1 - Funding Information:
This study, which was supported by research funds from the Japanese Ministry of Education, Culture, Sports, Science and Technology, was conducted as a part of the activities of the Research Institute of Sustainable Future Society, Waseda Research Institute for Science and Engineering, Waseda University.
Publisher Copyright:
© 2021 American Society of Civil Engineers.
PY - 2021/5/1
Y1 - 2021/5/1
N2 - Bentonite is planned for use as a buffer for repositories of high-level radioactive waste (HLW) because the buffer must have extremely low hydraulic conductivity to seal wastes. A Japanese HLW disposal facility might be built in a coastal area to facilitate waste transportation. Therefore, it is important to investigate the influence of seawater on bentonite buffer materials. This study used experiments to investigate the influence of artificial seawater on the hydraulic conductivities of three sodium-type bentonites and one calcium-type bentonite. This study assessed the influence of artificial seawater on hydraulic conductivities of bentonites in terms of the kinds of bentonite such as exchangeable-cation type, montmorillonite content, and the bentonite buffer dry density. Experimentally obtained results indicate a low influence of artificial seawater on hydraulic conductivities of sodium-type bentonites, provided that the compacted bentonite dry density is high. Furthermore, the author has proposed a mechanism of bentonite behavior in artificial seawater that results from cation filtration of montmorillonite mineral layers in bentonite. This study has also clarified the validity of the cations' filtration mechanism of montmorillonite mineral layers by comparing the calculated interlayer distance of montmorillonite minerals with the hydrated diameter of main cations in artificial seawater.
AB - Bentonite is planned for use as a buffer for repositories of high-level radioactive waste (HLW) because the buffer must have extremely low hydraulic conductivity to seal wastes. A Japanese HLW disposal facility might be built in a coastal area to facilitate waste transportation. Therefore, it is important to investigate the influence of seawater on bentonite buffer materials. This study used experiments to investigate the influence of artificial seawater on the hydraulic conductivities of three sodium-type bentonites and one calcium-type bentonite. This study assessed the influence of artificial seawater on hydraulic conductivities of bentonites in terms of the kinds of bentonite such as exchangeable-cation type, montmorillonite content, and the bentonite buffer dry density. Experimentally obtained results indicate a low influence of artificial seawater on hydraulic conductivities of sodium-type bentonites, provided that the compacted bentonite dry density is high. Furthermore, the author has proposed a mechanism of bentonite behavior in artificial seawater that results from cation filtration of montmorillonite mineral layers in bentonite. This study has also clarified the validity of the cations' filtration mechanism of montmorillonite mineral layers by comparing the calculated interlayer distance of montmorillonite minerals with the hydrated diameter of main cations in artificial seawater.
KW - Bentonite
KW - Clay minerals
KW - Hydraulic conductivity
KW - Radioactive waste disposal
KW - Seawater
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U2 - 10.1061/(ASCE)GT.1943-5606.0002513
DO - 10.1061/(ASCE)GT.1943-5606.0002513
M3 - Article
AN - SCOPUS:85102359716
SN - 1090-0241
VL - 147
JO - Journal of Geotechnical and Geoenvironmental Engineering
JF - Journal of Geotechnical and Geoenvironmental Engineering
IS - 5
M1 - 06021002
ER -