Swelling behaviors of GMZ bentonite–sand mixtures inundated in NaCl–Na2SO4 solutions

Cui, Suli; Zhang, Ming; Jia, Lingyan

doi:10.1016/j.nucengdes.2011.10.042

Cited by 47 publications

(4 citation statements)

References 17 publications

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“…7 shows a comparison between the experimental swelling pressure results of GMZ bentonite, and other GMZ and different types of bentonites. In this figure, two data sets of swelling pressure results for GMZ bentonite from China were investigated: GMZ-1 by Zhang et al (2012) and GMZ-2 by Cui et al (2012). Fig.…”

Section: Swelling Pressure and Dry Densitymentioning

confidence: 99%

Swelling pressure characteristics of compacted Chinese Gaomiaozi bentonite GMZ01

Schanz

Al-Badran

2014

Soils and Foundations

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Gaomiaozi bentonite (GMZ01) has been decided upon as the first option for use as buffer/backfill materials in the deep disposal of high-level radioactive waste in China. The basic functions of the materials used in the waste repositories request among others a sufficient swelling pressure and low hydraulic conductivity in order to provide long-term stability to the barrier system under environmental pressure and behavior of the waste loads. As such, it is necessary to investigate the influence of initial dry density on the swelling properties of Gaomiaozi bentonite (GMZ01) in order to achieve better design of buffer/backfill materials. In this study the swelling pressure of GMZ01 has been studied and analyzed by multi and one-step wetting constant volume tests with five different dry densities (1.15, 1.35, 1.50, 1.60 and 1.75 mg/m 3 ). Results show that swelling pressure changes with time nonlinearly, while there is a linear relationship between time/swelling pressure and time. Curves of swelling pressure and the amount of absorbed water varying with time can be classified into typical phases. For the GMZ01 tested here, the initial dry density is an important factor influencing the swelling pressure. The results show that there is an exponential relationship between swelling pressure and dry density. Moreover, comparison was done between the experimental swelling pressure results of used GMZ bentonite in this study and other bentonites cited in literature: (i) other GMZ's and (ii) different types of bentonites proposed as buffer/backfill materials (i.e., MX80, Kunigel, Montigel, and Calcigel). The effect on the microstructure of the density and the wetting under the constant volume condition (after the swelling pressure test) has been investigated by studying the results of pore size distribution for GMZ01 by using the mercury intrusion porosimetry (MIP) test and the environmental scanning electron microscope (ESEM) photos. Finally, two different theoretical concepts were used to estimate the swelling pressure (the modified DDL and thermodynamics approaches). The results of the two methods show that the swelling pressure results compare relatively well with the experimental data for the GMZ bentonite.

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Section: Swelling Pressure and Dry Densitymentioning

confidence: 99%

Swelling pressure characteristics of compacted Chinese Gaomiaozi bentonite GMZ01

Schanz

Al-Badran

2014

Soils and Foundations

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“…[7][8][9][10] the maximum swelling pressure of bentonite decayed exponentially with increasing sand admixture, while the maximum swelling rate of bentonite declined as a quadratic function. 8,[11][12][13] Due to its stable geological structure and sparse population distribution, the Beishan region of Gansu Province in China is the preferred and ideal area for building high-level nuclear waste disposal depots. The hydrochemical analysis indicated that the groundwater in this area had a relatively high salt content.…”

Section: Introductionmentioning

confidence: 99%

A novel coupled hydrothermal–mechanical model and numerical analysis of unsaturated bentonite considering the influence of salt ions

Chen,

Jin,

Wang

et al. 2024

AIP Advances

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The quantitative research on swelling properties of bentonite considering the influence of salt ions under the effect of hydrothermo-mechanical coupling is relatively weak. Based on a calculation model for the swelling characteristics of bentonite from a fractal perspective, this work proposes a novel coupled multifield control equation for unsaturated bentonite considering the influence of salt ions. The numericalization of the coupling control equation was completed by secondary development of a numerical analysis platform. The new theoretical model’s dependability and validity were validated by comparing it to experimental data. The evolution of the related-field quantities under the multifield coupled effect in salt-bearing environments was obtained, and the effect of salt ion concentration was analyzed. The calculation showed that the temperature of bentonite changed periodically with changing ambient temperature. Temperature gradient induces migratory movement of water from high to low temperature regions. The hollow axisymmetric soil sample gradually saturated from outside to inside with increasing water injection rate at the outer cylindrical surface. The swelling pressure of bentonite will increase with an increase in water content, whereas the presence of salt ions weakened the swelling behavior. Temperature and relative humidity were less affected by salt ion concentration.

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“…Karnland et al found that a bentonite-sand mixture and NaCl solution gave rise to an increase in hydraulic conductivity and a decrease in the expansion force [18]. Zhang et al studied NaCl-Na 2 SO 4 solutions of different TDS on the expandability of GMZ bentonite mixed with quartz and found the maximum expansion force had a linear reduction with increasing TDS [19]. Nakayama et al measured the rate of dissolving montmorillonite with an alkaline solution tank [20].…”

Section: Introductionmentioning

confidence: 99%

Swelling Properties and Permeability of GMZ Bentonite-Sand Mixtures during Different Solutions Infiltration

Wang

Zhao

et al. 2021

Sustainability

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In China, Gaomiaozi (GMZ) bentonite is recognized as a barrier material for isolating nuclear waste. Different chemical solutions may change the hydraulic conductivity and swelling capacity of bentonite. Consequently, a series of swelling pressure and permeability experiments was carried out on bentonite-sand mixtures with various dry densities and infiltrating solutions. X-ray diffraction (XRD) and the field emission scanning electron microscope (FESEM) were carried out on the samples experiencing the tests to identify the influence of chemistry pore solutions upon the mineralogical and microstructure changes. The results show that the swelling pressure experienced rapid swelling, slow expansion, and the stable expansion stage for the specimens of infiltrating solutions except for NaOH. For the specimens infiltrated with NaOH solutions, the swelling pressure experienced rapid increases, slow decreases, and a stable development stage. With hyper-alkaline and hyper-salinity infiltration, the swelling pressure decreased, and the permeability increased. In addition, swelling pressure attained stability more quickly on contact with hyper-alkaline and hyper-salinity solutions. Comparing the test results, the results indicate that the influence of NaOH on the expansion and permeability was higher than NaCl-Na2SO4 at the same concentration.

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Swelling behaviors of GMZ bentonite–sand mixtures inundated in NaCl–Na2SO4 solutions

Cited by 47 publications

References 17 publications

Swelling pressure characteristics of compacted Chinese Gaomiaozi bentonite GMZ01

Swelling pressure characteristics of compacted Chinese Gaomiaozi bentonite GMZ01

A novel coupled hydrothermal–mechanical model and numerical analysis of unsaturated bentonite considering the influence of salt ions

Swelling Properties and Permeability of GMZ Bentonite-Sand Mixtures during Different Solutions Infiltration

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