• Title, Summary, Keyword: Bentonite

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Geotechnical Properties of Soil-Bentonite Mixtures (흙-벤토나이트 혼합물의 지반공학적 특성)

  • 채교익;권무남
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.43 no.5
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    • pp.132-144
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    • 2001
  • Iln order to figure out criteria of bentonite for using as impervious material of waste landfill, laboratory experiments were performed to reveal the geotechnical properties of soil-bentonite mixtures such as compaction test, direct shear test, unconfined compression test, triaxial compression test, consolidation test and permeability test. The results of the study are summarized as follows ; 1. Based on the compaction test, optimum moisture content increased with the increase of bentonite content, but maximum dry density decreased. 2. In unconfined compression test, the maximum strength of the soil-bentonite mixtures appeared at 10% bentonite content. The correlation equation between stress($\sigma$) and strain($\varepsilon$) of the soil-bentonite mixtures is given by ; $\sigma=\frac{a\cdot\varepsilon}{\varepsilon^n+b}$ 3. In shear test of the mixtures. the shear strength showed an increasing trend with increase of bentonite content and the maximum shear strength appeared at 10% bentonite content. 4. In consolidation test, the coefficient of compressibility $(a_v)$$(m_v)$$(C_v)$

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An Experimental Study on the Strength-Development Properties of Mortar with Discarded Bentonite Powder (폐 벤토나이트 분말을 흔입한 모르터의 강도 발현 특성에 관한 실험적 연구)

  • 정민수;김효열;안재철;강병희
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.23.2-29
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    • 2003
  • As the bentonite is main material to prevent from collapse of drilling hole at underground excavation works, the quantity of bentonite is increasingly used on construction industry day by day. But, the discarded bentonite that is excessively used at underground excavation works causes various environmental trouble such as soil and water pollution etc. Therefore, this study aims to propose a foundamental report about pozzolan reaction of discarded Bentonite powder by heat-treatment and cooling as concrete mineral admixture. To find out the strength-development properties of mortar with discarded Bentonite powder by indirect cooling & cooling using of water after heat-treatment, the experiments such as flow test, and compressive strength test on curing age of mortar are excuted. As a result of this study, discarded Bentonite powder can be utilized as concrete mineral admixture by heat-treatment and especially, the strength-development properties of mortar mixing with discarded Bentonite powder is superior to the situation of $600^{\circ}C$.60min-cooling using of water.

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Permeability of Soil-Bentonite Mixtures (흙-벤토나이트 혼합물의 투수특성)

  • 채교익;권무남;이상호;남효석
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.45 no.1
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    • pp.55-62
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    • 2003
  • Leachate generated from landfill material flows through soil gravitationally downward and. continues to flow until it encounters groundwater, posing the thread of pollution. So selection of liner material having a low permeability and testing method are required. The study was performed to find bentonite content of soil-bentonite mixtures for using as liner and cover of waste landfills. This paper includes results of consolidation tests and permeability tests and evaluates suitability and properties of soil-bentonite mixtures as impervious materials.

Water Diffusion and Resaturation in Unsaturated Compacted Bentonite (불포화 압축 벤토나이트에서의 수확산 및 재포화)

  • 고은옥;이재완;조원진;현재혁;전관식
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • pp.216-220
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    • 1998
  • Experimental studies were carried out to investigate water diffusion in unsaturated compacted bentonite for a landfill of hazardous wastes. Water content distributions were measured and water diffusion coefficients were determined when the dry densities of compacted bentonite were in the range of 1.4 - 1.8 g/㎤. Resaturation times were also calculated to analyze the ability of the compacted bentonite to retard water movement. The results obtained were as follows: Diffusion model described properly the water migration in unsaturated compacted bentonite. Water diffusion coefficients ranged from 4.30$\times$10$^{-6}$ $\textrm{cm}^2$/sec to 1.93$\times$10$^{-6}$ $\textrm{cm}^2$/sec, and decreased with increasing the dry density. The dry density of compacted bentonite was found to be an important factor to control the resaturation time by water. This study suggests that the domestic compacted bentonite should be a good barrier material against water movement in a landfill of hazardous wastes.

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Permeability Characteristics of Sand- Bentonite Mixtures

  • Chang, Pyoung-Wuck;Chae, Yong-Suk
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.39 no.2
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    • pp.26-31
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    • 1997
  • Abstract A series of permeability tests was performed on the mixtures with specific mixing rates of sand and bentonite using modified rigid-wall permeameter. Sand-bentonite mixtures were permeated by organics, ethanol and TCE. Permeability of bentonite with several mixing rates had a tendency to decrease up to initial one pore volume and permeability was thereafter converged to a constant value. When sand-bentonite mixtures was permeated by water, permeability was decreased at the beginning but it was thereafter converged to a constant. Among several mixing rates, permeability was greatly decreased at 15% of mixing rate. When sand-bentonite mixtures with 15% mixing rate was permeated by ethanol, permeability was about 10 times larger value than permeability of water. Peameability was shown greater values when permeated by TCE (TrichloroEthylene) followed by ethanol. Suitable mixing rate of sand-bentonite for a liner of waste landfills was detected.

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A study on the Evaluation of Permeability and Structure for Calcium Bentonite-Sand Mixtures (칼슘 벤토나이트-모래 혼합차수재의 투수 및 구조 특성에 관한 연구)

  • Yun, Seong Yeol;An, Hyeon Kyu;Oh, Minah;Lee, Jai-Young
    • Journal of the Korean Geosynthetics Society
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    • v.18 no.2
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    • pp.1-10
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    • 2019
  • This study was intended to evaluate the water permeability and structure for calcium bentonite-sand mixtures to utilize calcium bentonite as a liner. This study conducted physico-chemical properties tests, compaction tests, permeability test and Scanning Electron Microscopy analysis (SEM) analysis. It was found the higher the ratio of calcium bentonite, the lower the dry density with coefficient of permeability, and the higher the optimum moisture content. In particular, SEM analysis was found the higher the ratio of calcium bentonite, the higher the area of the montmorillonite particles. In conclusion, the optimum coefficient of permeability that finds the landfill liner condition (must be less than $1{\times}10^{-7}cm/sec$) was obtained when the ratio of calcium bentonite was 40% or higher. These findings may improve the understanding of the calcium bentonite as a liner. Calcium bentonite shows a similar permeability to sodium bentonite 7% when mixed at 40% or more. Therefore, it is considered that calcium bentonite can be utilized as a liner.

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.

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.

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.

Comparison of the effect of lithium bentonite and sodium bentonite on the engineering properties of bentonite-cement-sodium silicate grout

  • Zhou, Yao;Wang, Gui H.;Chang, Yong H.
    • Advances in concrete construction
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    • v.9 no.3
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    • pp.279-287
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    • 2020
  • This paper focuses on the engineering properties of Bentonite-Cement-Sodium silicate (BCS) grout, which was prepared by partially replacing the ordinary Portland cement in Cement-Sodium silicate grout with lithium bentonite (Li-bent) and sodium bentonite (Na-bent), respectively. The effect of different Water-to-Solid ratio (W/S) and various replacement percentages of bentonite on the apparent viscosity, bleeding, setting time, and early compressive strength of BCS grout were investigated. The XRD method was used to detect its hydration products. The results showed that both bentonites played a positive role in the stability of BCS grout, increased its apparent viscosity. Na-bent prolonged the setting time of BCS, while 5% of Li-bent shortened the setting time of BCS. The XRD analysis indicated that the hydration products between the mixture containing Na-bent and Li-bent did not differ much. Using bentonite as supplementary cementitious material (SCM) to replace partial cement is a promising way to cut down on carbon dioxide emissions and to produce low-cost, eco-friendly, non-toxic, and water-resistant grout. In addition, Li-bent was superior to Na-bent in improving the strength and the thickening of BCS grouts.