Econ. Environ. Geol. 2022; 55(3): 219-229

Published online June 30, 2022

https://doi.org/10.9719/EEG.2022.55.3.219

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

A Literature Review on Studies of Bentonite Alteration by Cement-bentonite Interactions

Ja-Young Goo1,2, Jin-Seok Kim1, Jang-Soon Kwon1, Ho Young Jo2,*

1Disposal Performance Demonstration Research Division, Korea Atomic Energy Research Institute (KAERI), Republic of Korea
2Department of Earth and Environmental Sciences, Korea University, Republic of Korea

Correspondence to : *hyjo@korea.ac.kr

Received: April 13, 2022; Revised: May 25, 2022; Accepted: May 26, 2022

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

Bentonite is being considered as a candidate for buffer material in geological disposal systems for high-level radioactive wastes. In this study, the effect of cement-bentonite interactions on bentonite alteration was investigated by reviewing the literature on studies of cement-bentonite interactions. The major bentonite alteration by hyperalkaline fluids produced by the interaction of cementitious materials with groundwater includes cation exchange, montmorillonite dissolution, secondary mineral precipitation, and illitization. When the hyperalkaline leachate from the reaction of the cementitious material with the groundwater comes into contact with bentonite, montmorillonite, the main component of bentonite, is dissolved and a small amount of secondary minerals such as zeolite, calcium silicate hydrate, and calcite is produced. When montmorillonite is continuously dissolved, the physicochemical properties of bentonite may change, which may ultimately causes changes in bentonite performance as a buffer material such as adsorption capacity, swelling capacity, and hydraulic conductivity. In addition, the bentonite alteration is affected by various factors such as temperature, reaction period, pressure, composition of pore water, bentonite constituent minerals, chemical composition of montmorillonite, and types of interlayer cations. This study can be used as basic information for the long-term stability verification study of the buffer material in the geological disposal system for high-level radioactive wastes.

Keywords bentonite, buffer, cement, alteration, hyperalkaline fluid, radionuclides, performance

시멘트-벤토나이트 상호작용에 의한 벤토나이트 변질 연구사례 분석

구자영1,2 · 김진석1 · 권장순1 · 조호영2,*

1한국원자력연구원 처분성능실증연구부
2고려대학교 지구환경과학과

요 약

벤토나이트는 고준위방사성폐기물 심층처분 시스템 내 완충재 후보물질로서 고려되고 있다. 본 연구에서는 시멘트-벤토나이트의 상호작용 연구에 관한 문헌을 검토하여, 시멘트-벤토나이트 상호작용이 벤토나이트 변질 및 장기 안정성에 미치는 영향을 살펴보았다. 시멘트 물질과 지하수 상호작용에 의해 생성되는 강염기성 유체에 의한 벤토나이트의 주요 변질작용은 양이온 교환, 몬모릴로나이트 용해, 2차 광물 침전, 일라이트화 등이다. 처분장 인근 암반 단열을 통해 유입된 지하수와 처분장 건설에 사용된 시멘트 물질이 접촉하여 생성된 강염기성의 침출수가 벤토나이트와 반응하면 벤토나이트의 주구성광물인 몬모릴로나이트와 부구성광물의 용해가 발생하고, 제올라이트, 규산칼슘수화물, 방해석 등의 2차 광물의 침전이 일어난다. 몬모릴로나이트가 지속적으로 용해되면 벤토나이트의 물리화학적 특성이 변할 수 있고, 이는 궁극적으로 흡착능, 팽윤능, 투수성 등 완충재로서의 벤토나이트 성능 변화를 초래할 수 있다. 또한, 벤토나이트의 변질은 온도, 반응 기간, 압력, 공극수의 조성, 벤토나이트 구성광물, 몬모릴로나이트 화학조성, 층간 양이온 종류 등의 다양한 요인에 영향을 받는다. 본 연구는 고준위방사성폐기물 심층처분 시스템 내 완충재의 장기 안정성 검증 연구를 위한 기초 자료로서 활용될 수 있다.

주요어 벤토나이트, 완충재, 시멘트, 변질, 강염기성 유체, 핵종, 성능

Article

Review

Econ. Environ. Geol. 2022; 55(3): 219-229

Published online June 30, 2022 https://doi.org/10.9719/EEG.2022.55.3.219

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

A Literature Review on Studies of Bentonite Alteration by Cement-bentonite Interactions

Ja-Young Goo1,2, Jin-Seok Kim1, Jang-Soon Kwon1, Ho Young Jo2,*

1Disposal Performance Demonstration Research Division, Korea Atomic Energy Research Institute (KAERI), Republic of Korea
2Department of Earth and Environmental Sciences, Korea University, Republic of Korea

Correspondence to:*hyjo@korea.ac.kr

Received: April 13, 2022; Revised: May 25, 2022; Accepted: May 26, 2022

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

Bentonite is being considered as a candidate for buffer material in geological disposal systems for high-level radioactive wastes. In this study, the effect of cement-bentonite interactions on bentonite alteration was investigated by reviewing the literature on studies of cement-bentonite interactions. The major bentonite alteration by hyperalkaline fluids produced by the interaction of cementitious materials with groundwater includes cation exchange, montmorillonite dissolution, secondary mineral precipitation, and illitization. When the hyperalkaline leachate from the reaction of the cementitious material with the groundwater comes into contact with bentonite, montmorillonite, the main component of bentonite, is dissolved and a small amount of secondary minerals such as zeolite, calcium silicate hydrate, and calcite is produced. When montmorillonite is continuously dissolved, the physicochemical properties of bentonite may change, which may ultimately causes changes in bentonite performance as a buffer material such as adsorption capacity, swelling capacity, and hydraulic conductivity. In addition, the bentonite alteration is affected by various factors such as temperature, reaction period, pressure, composition of pore water, bentonite constituent minerals, chemical composition of montmorillonite, and types of interlayer cations. This study can be used as basic information for the long-term stability verification study of the buffer material in the geological disposal system for high-level radioactive wastes.

Keywords bentonite, buffer, cement, alteration, hyperalkaline fluid, radionuclides, performance

시멘트-벤토나이트 상호작용에 의한 벤토나이트 변질 연구사례 분석

구자영1,2 · 김진석1 · 권장순1 · 조호영2,*

1한국원자력연구원 처분성능실증연구부
2고려대학교 지구환경과학과

Received: April 13, 2022; Revised: May 25, 2022; Accepted: May 26, 2022

요 약

벤토나이트는 고준위방사성폐기물 심층처분 시스템 내 완충재 후보물질로서 고려되고 있다. 본 연구에서는 시멘트-벤토나이트의 상호작용 연구에 관한 문헌을 검토하여, 시멘트-벤토나이트 상호작용이 벤토나이트 변질 및 장기 안정성에 미치는 영향을 살펴보았다. 시멘트 물질과 지하수 상호작용에 의해 생성되는 강염기성 유체에 의한 벤토나이트의 주요 변질작용은 양이온 교환, 몬모릴로나이트 용해, 2차 광물 침전, 일라이트화 등이다. 처분장 인근 암반 단열을 통해 유입된 지하수와 처분장 건설에 사용된 시멘트 물질이 접촉하여 생성된 강염기성의 침출수가 벤토나이트와 반응하면 벤토나이트의 주구성광물인 몬모릴로나이트와 부구성광물의 용해가 발생하고, 제올라이트, 규산칼슘수화물, 방해석 등의 2차 광물의 침전이 일어난다. 몬모릴로나이트가 지속적으로 용해되면 벤토나이트의 물리화학적 특성이 변할 수 있고, 이는 궁극적으로 흡착능, 팽윤능, 투수성 등 완충재로서의 벤토나이트 성능 변화를 초래할 수 있다. 또한, 벤토나이트의 변질은 온도, 반응 기간, 압력, 공극수의 조성, 벤토나이트 구성광물, 몬모릴로나이트 화학조성, 층간 양이온 종류 등의 다양한 요인에 영향을 받는다. 본 연구는 고준위방사성폐기물 심층처분 시스템 내 완충재의 장기 안정성 검증 연구를 위한 기초 자료로서 활용될 수 있다.

주요어 벤토나이트, 완충재, 시멘트, 변질, 강염기성 유체, 핵종, 성능

    Fig 1.

    Figure 1.Schematic diagram of deep geological repository system (KBS-3) (modified from Posiva, 2010).
    Economic and Environmental Geology 2022; 55: 219-229https://doi.org/10.9719/EEG.2022.55.3.219

    Fig 2.

    Figure 2.Schematic diagrams (a) and diagrammatic sketch (b) of the montmorillonite structure (from Grim 1968).
    Economic and Environmental Geology 2022; 55: 219-229https://doi.org/10.9719/EEG.2022.55.3.219

    Fig 3.

    Figure 3.Bentonite-cement interaction as a coupled non-linear system (modified from Savage et al., 2007).
    Economic and Environmental Geology 2022; 55: 219-229https://doi.org/10.9719/EEG.2022.55.3.219

    Fig 4.

    Figure 4.Schematic diagram of the potential sequence of secondary minerals due to migration of hyperalkaline pore fluids through bentonite (modified from Savage et al., 2007).
    Economic and Environmental Geology 2022; 55: 219-229https://doi.org/10.9719/EEG.2022.55.3.219

    Table 1 . Summary of experimental conditions for studies of bentonite-alkaline liquid interactions and secondary minerals formed by the interactions.

    MaterialSolutionTemp.(°C)Time (days)Pressure (atm)Secondary mineralReference
    FEBEX bentonitepH 13.5; 0.17 M Na, 0.33 M K, 4.07 M Ca35, 60, 9030-3601Na-phillipsiteVilla et al. (2001)
    pH 13.5 to 10; several tests with Na, Ca, K at different concentrations30, 60, 907-3651phillipsite, analcime, Mg-smectite, CSH-gel phasesRamirez et al. (2002)
    0.1 M, 0.25 M, 0.5M NaOH + Ca(OH)225, 75, 125, 20030-540analcime, tobermorite or CSH-gel, gyrolite, phillipsite, saponiteCuevas et al. (2006)
    pH 12.9-13.5; 0.1-0.5 M NaOH + Ca(OH)225-20030-5401analcime (125-200°C), phillipsite (75°C), gel-CSH (25-125°C), tobermorite (125-200°C), gyrolite (200°C)Sánchez et al. (2006)
    pH 13.5; K-Na-OH type90chloriteFernández et al. (2013)
    pH 13.4; K-Na-OH-type-17515 months1analcime, K-feldspar, mixed layered illite/smectiteFernández et al. (2014)
    MX-80 bentonitepH 13.4; K-Na-OH-type-17515 months1analcime, K-feldspar, mixed layered illite/smectiteFernández et al. (2014)
    3 M KOH352701illite (+25%)Eberl et al. (1993)
    1 M KOH60, 90, 1201, 71 atm at 60 and 90°C,phillipsite, beidelliteBouchet et al. (2004)
    1 M NaOH60, 90, 1201, 7 1 atm at 120°Canalcime, beidellite
    1.0-0.3 M NaOH23701beidelliteKarnland (2004)
    Smectite(Ceca and Ibeco)KOH > 4 M351initial product: illite (+45%) sequence: mica, phillipsite, K-feldspar, quartzBauer and Berger (1998)
    KOH > 4 M801initial product: illite (+90%) sequence: mica, phillipsite, K-feldspar, quartz
    Montmorillonite + quartzpH 13 to 14; Na-K type50-170up to 1251analcimeNakayama et al. (2004)
    Na–Ca smectite, Na-smectite, Ca-smectitepH 12; NaOH150605-150 barno evolution. buffer effect of the final clay pH 9Mosser-Ruck and Cathelineau (2004)
    pH 11.7; 3 M KOH + KCl150605-150 barillite/smectite mixed layer, low- and high charge smectite layer, quartz, feldspar
    pH 11.7; 1 M K2CO3150605-150 bartobermorite (CSH), merlinoite (zeolite)
    Opalinus Clay (Mont Terri)pH 13 and 12; NaOH150, 175, 200401analcime, vermiculite, Na-rectoriteChermak (1992)
    pH 13 and 12; KOH150, 175, 200501phillipsite, K-feldspar, K-rectoriteChermak (1993)
    GMZ bentonitepH 12-13; degraded by ordinary portland cement20551C-S-H gels and analcimeSun et al. (2018)
    1 M KOH35, 8020-801KaolinitizationYe et al. (2016)

    KSEEG
    Apr 30, 2024 Vol.57 No.2, pp. 107~280

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