Effects of synthetic site water on bentonite-concrete system for a potential nuclear waste repository

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外文摘要：In high-level nuclear waste(HLW)repositories,concrete and compacted bentonite are designed to be employed as buffer materials,which may raise a problem of interactions between concrete and bentonite.These interactions would lead to mineralogy transformation and buffer performance decay of bentonite under the near field environment conditions in a repository.A small-scale experimental setup was established to simulate the concrete-bentonite-site water interaction system from a potential nu-clear waste repository in China.Three types of mortars were prepared to correspond to the concrete at different degradation states.The results permit the determination of the following:(1)The macro-properties of Gaomiaozi(GMZ)bentonite(e.g.swelling pressure,permeability,the final dry density,and water content of reacted samples);(2)The composition evolution of fluids from the synthetic site water-concrete-bentonite interaction systems;(3)The sample characterization including Fourier trans-form infrared spectroscopy(FTIR)and X-ray powder diffraction(XRD).Under the infiltration of the synthesis Beishan site water(BSW),the swelling pressure of bentonite decreases slowly with time after reaching its second swelling peak.The flux decreases with time during the infiltrations,and it tends to be stable after more than 120 d.Due to the cation exchange reactions in the BSW-concrete-bentonite systems,the divalent cations(Ca and Mg)were consumed,and the monovalent cations(Na and K)were released.The dissolution of minerals in the bentonite such as albite causes Si increasing in the pore water.It was concluded that the hydro-mechanical property degradation of bentonite takes place when it comes into contact with concrete mortar,even under low-pH groundwater conditions.The soil disper-sion,the uneven water content,and the uneven dry density in bentonite samples may partly contribute to the swelling decay of bentonite.Therefore,the direct contact with concrete has an obvious effect on the performance of bentonite.

外文关键词：

Mock-up deviceGMZ bentoniteSite water-concrete-bentonite systemGeochemistryBuffer performance

作者：

Zhao Sun、Yong-Gui Chen、Wei-Min Ye、Qiong Wang、Dong-Bei Wu、Zhen-Yu Yin

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作者单位：

Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Department of Geotechnical Engineering,Tongji University,Shanghai,200092,China

Department of Civil and Environmental Engineering,The Hong Kong Polytechnic University,Hung Hom,Kowloon,Hong Kong,China

School of Chemical Science and Engineering,Tongji University,Shanghai,200092,China

基金：

National Natural Science Foundation of ChinaInnovation Program of Shanghai Municipal Education CommissionFund of the Shanghai Science and Technology CommissionTop Discipline Plan of Shanghai Universities-Class I and the Fundamental Research Funds for the Central UniversitiesInternational Post-Doc Fund of The Hong Kong Polytechnic University is greatly appreciated

项目编号：

421257012023ZKZD2622DZ2201200

出版年：

2024

DOI：

10.1016/j.jrmge.2024.01.027

岩石力学与岩土工程学报(英文版)

中国科学院武汉岩土力学所中国岩石力学与工程学会武汉大学

岩石力学与岩土工程学报(英文版)

CSTPCD

影响因子：0.404

ISSN：1674-7755

年,卷(期)：2024.16(9)