• Title/Summary/Keyword: Korean bentonite

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The Study on the Compressive Strength Properties of Mortar using Discarded Bentonite Powder by the Cooling Method after Heat Treatment (폐벤토나이트 분말의 소성 및 냉각조건에 따른 모르터의 압축강도 발현특성에 관한 연구)

  • Kim, Hyo-Youl
    • Journal of the Korea Institute of Building Construction
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    • v.4 no.4
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    • pp.87-94
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    • 2004
  • As the bentonite is main material to prevent from collapse of drilling hole at underground excavation works, it is increased using quantity on construction industry day by day. But, the discarded bentonite that is over using at underground excavation works is caused various enviromental trouble as soil and water pollution est. Therefore, this study aims to propose a foundamental report for pozzolan reaction of discarded Bentonite powder by heat-treatment and cooling as concrete mineral admixture. To find out pozzolan reaction ability of discarded Bentonite powder by indirect cooling & cooling using of water after heat-treatment, the experiments are excuted flow test & compressive strength on age of mortar using discarded Bentonite powder. As a result of this study, discarded Bentonite powder can be utilized as concrete mineral admixture by heat-treatment and especially, pozzolan reaction ability of discarded Bentonite powder is superior to the situation of 600℃. 60min & cooling using of water.

A Correlation to Predict the Thermal Conductivity of Buffer and Backfill Material for a High-Level Waste Repository (고준위폐기물처분장 완충재 및 뒷채움재의 열전도도 예측을 위한 관계식)

  • Cho, Won-Jin;Lee, Jae-Owan;Kwon, Sang-Ki
    • Tunnel and Underground Space
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    • v.20 no.4
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    • pp.284-291
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    • 2010
  • In the present design concept of a high-level waste repository, the bentonite and bentonite-sand mixture are considered as the buffer and backfill material. For the Kyungju bentonite which is a candidate material, the thermal conductivities of compacted bentonite and bentonite-sand mixture were measured. A correlation has been proposed to predict the thermal conductivity of the Kyungju bentonite and the bentonite-sand mixture as a function of the dry density, the water content and the sand fraction. The proposed correlation can predict the thermal conductivity with a difference less than 10% under the experimental conditions.

An Experimental Study on the Pozzolan Reaction of discarded Bentonite by the Cooling Method after Heat Treatment (소성가공한 폐 벤토나이트 분말의 냉각방법에 따른 포졸란 반응성에 관한 실험적 연구)

  • Kim, Hyo-Yeul;Kang, Byeung-Hee
    • Journal of the Korea Institute of Building Construction
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    • v.2 no.3
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    • pp.139-146
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    • 2002
  • As the bentonite is main material to prevent from collapse of drilling hole at underground excavation works, it is increased using quantity on construction industry day by day. But, the discarded bentonite that is over using at underground excavation works is caused various environmental trouble as soil and water pollution est. This study aims to propose a foundamental report for pozzolan reaction of discarded Bentonite powder by heat-treatment and cooling as concrete mineral admixture. To find out pozzolan reaction ability of discarded Bentonite powder by indirect cooling & cooling using of water after heat-treatment, the experiments are excuted Phenolphtalein test, setting test, pH test and the analysis by X-ray diffractor. As a result of this study, discarded Bentonite powder can be utilized as concrete mineral admixture by heat-treatment and especially, pozzolan reaction ability of discarded Bentonite powder is superior to the situation of 50$0^{\circ}C$~$700^{\circ}C$, 60min.

Effect of Exchangeable Cation on Radionuclide Diffusion In Compacted Bentonite

  • Park, Jong-Won;Park, Hyun-Soo;Dennis W. Oscarson
    • Nuclear Engineering and Technology
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    • v.28 no.3
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    • pp.274-279
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    • 1996
  • Diffusion coefficient is a critical parameter for predicting radiological source term(migration rate and flux of radionuclide) through given near field conditions in spent fuel or high level waste repository. The effect of exchangeable cation-$Na^+$ and $Ca^{2+} - on the diffusion of $I^- \;and^3H$ (as HTO) in compacted bentonite was examined using a through-diffusion method. Bentonite material used here was compacted to a density of 1.3 Mg/m$^3$, and Na-bentonite was saturated with a solution of 100 mol NaCl/m$^3$ and Ca-bentonite with 50 $mol\;CaCl_2$/m$^3$. The results show that effective diffusion coefficients are generally higher by a factor of two to five in Ca-than Na-clay. This is attributed to the larger particle size of Ca-compared to Na-bentonite; hence, Ca-bentonite has a greater proportion of relatively large pores, which make a greater contribution to mass transport than small pores. Although the nature of the exchangeable cation affects mass diffusion in compacted bentonite, the effect is small and not likely to influence performance assessment modeling of compacted bentonite-based barriers.

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A Compilation and Evaluation of Thermal and Mechanical Properties of Bentonite-based Buffer Materials for a High- level Waste Repository

  • Cho, Won-Jin;Lee, Jae-Owan;Kang, Chul-Hyung
    • Nuclear Engineering and Technology
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    • v.34 no.1
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    • pp.90-103
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    • 2002
  • The thermal and mechanical properties of compacted bentonite and bentonite-sand mixture were collected from the literatures and compiled. The thermal conductivity of bentonite is found to increase almost linearly with increasing dry density and water content of the bentonite. The specific heat can also be expressed as a function of water ontent, and the coefficient of thermal expansion is almost independent on the dry density. The logarithm of unconfined compressive strength and Young’s modulus of elasticity increase linearly with increasing dry density, and in the case of constant dry density, it can be fitted to a second order polynomial of water content. Also the unconfined compressive strength and Young’s modulus of elasticity of the bentonite-sand mixture decreases with increasing sand content. The Poisson’s ratio remains constant at the dry density higher than 1.6 Mg/m$_3$, and the shear strength increases with increasing dry density.

Remediation of PCE-contaminated Groundwater Using Permeable Reactive Barrier System with M0M-Bentonite (MOM-Bentonite 투수성반응벽체를 이용한 PCE로 오염된 지하수의 정화)

  • Chung, Sung-Lae;Lee, Dal-Heui
    • Journal of Soil and Groundwater Environment
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    • v.17 no.4
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    • pp.73-80
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    • 2012
  • The objectives of this research were to study the applicability and limitations of permeable reactive barrier (PRB) for the removal of tetrachloroethylene (PCE) from the groundwater. PRB column tests were conducted using reactive material with Moringa Oleifera Mass - Bentonite (Mom-Bentonite). Most of the PCE in the groundwater was degraded and/or captured (sorpted) in the zone containing activated material (MOM-Bentonite). The removal rate of PCE from the groundwater was 90% and 75% after 30 days and 180 days, respectively. The effect of micro-organisms on the long-term permeability and reactivity of the barrier is not well understood. MOM-Bentonite PRB system in this research has the potential to be developed into an environmentally and economically acceptable technology for the in situ remediation of PCE-contaminated groundwater.

Thermal conductivity and viscosity of graphite-added bentonite grout for backfilling ground heat exchanger (지중 열교환기용 뒤채움재로서 흑연을 첨가한 벤토나이트 그라우트재의 열전도도 및 점도 특성)

  • Lee, Chul-Ho;Lee, Kang-Ja;Choi, Hang-Seok;Choi, Hyo-Pum
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.5 no.1
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    • pp.19-24
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    • 2009
  • Bentonite-based grouting has been usually used for sealing a borehole installed for a closed-loop vertical ground heat exchanger in a geothermal heat pump system (GHP) because of its high swelling potential and low hydraulic conductivity. The bentonite-based grout, however, has relatively lower thermal conductivity than that of ground formation. Accordingly, it is common to add some additives such as silica sand into the bentonite-based grout for enhancing heat transfer. In this study, graphite is adapted to substitute silica sand as an addictive because graphite has very high thermal conductivity. The effect of graphite on the thermal conductivity of bentonite-based grouts has been quantitatively evaluated for seven bentonite grouts from different product sources. In addition, the viscosity of graphite-added bentonite grout was measured to evaluate the field pumpability of the grout.

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Utilization of Mineral Oxides to Attenuate Mn-EDTA and Fluoride (산화광물을 이용한 수중의 망간-EDTA, 불소 제거)

  • 현재혁;남인영
    • Journal of Korea Soil Environment Society
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    • v.1 no.2
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    • pp.51-60
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    • 1996
  • Removal of Mn-EDTA complex and fluoride by use of hematite and ferrite, which are the by-product to be disposed of as industrial wastes, was investigated. For the comparison of removal rate, Na-bentonite known as excellent absorbent of inorganic contaminants was included in the experiments. As the results of batch mode experiments, for manganese, ferrite-A revealed 48∼65% of removal capacity, ferrite-B 46∼57%, hematite 17∼26%, while Na-bentonite showed 10∼23% of removal, depending on the initial concentration. Meanwhile, in case of fluoride : hematite revealed 53 ∼63% of removal : ferrite-A 54∼63 %, while ferrite-B did 20∼38 %. From the results, it can be postulated that the capacity of hematite and ferrite to attenuate inorganic pollutants, especially when they form complex ions, is superior to that of Na-bentonite. Consequently, the mixing of such oxide minerals with Na-bentonite will reinforce the function of Na-bentonite, especially in the undergroud liner aspect.

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Improvement of Adsorbability of Methylene Blue on Bentonite Treated with Electrolyte Solution (Bentonite의 전각질수용액 처리에 의한 Methylene Blue 흡착성 개선)

  • 신병식;김면섭
    • Journal of the Korean Ceramic Society
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    • v.11 no.2
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    • pp.11-16
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    • 1974
  • Korean Yung-il bentonite was treated with potassium chloride, zinc chloride, calcium chloride, ferric chloride, or chromic chloride solutions respectively varying their concentration, treating temperature and treating time. The adsorbabilities of methylene blue on these pretreated bentonite were investigated. In the case of treatment with potassium chloride solution, the improvement of the adsorbahility of methylene blue on the products was observed, and in the best result the adsorbability was 1.6 times better than that on the original bentonite. With zinc chloride solution, the optimum adsorbability was a value of 1.7 times better than that on the original bentonite. With ferric chloride, chromic chloride or calcium chloride solution, slight improvement of the adsorbability was observed.

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Evaluation of Water Suction for Compacted Bentonite Buffer Under Elevated Temperature Conditions

  • Yoon, Seok;Lee, Deuk-Hwan;Cho, Won-Jin;Lee, Changsoo;Cho, Dong-Keun
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.20 no.2
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    • pp.185-192
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    • 2022
  • A compacted bentonite buffer is a major component of engineered barrier systems, which are designed for the disposal of high-level radioactive waste. In most countries, the target temperature required to maintain safe functioning is below 100℃. If the target temperature of the compacted bentonite buffer can be increased above 100℃, the disposal area can be dramatically reduced. To increase the target temperature of the buffer, it is necessary to investigate its properties at temperatures above 100℃. Although some studies have investigated thermal-hydraulic properties above 100℃, few have evaluated the water suction of compacted bentonite. This study addresses that knowledge gap by evaluating the water suction variation for compacted Korean bentonite in the 25-150℃ range, with initial saturations of 0 and 0.22 under constant saturation conditions. We found that water suction decreased by 5-20% for a temperature increase of 100-150℃.