• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.497-504
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• 1999

This study presents the physical and engineering characteristics of soil-bentonite admixed liner in I landfill. Main focus was the hydraulic conductivity of compacted soil-bentonite admixed and mechanisms governing low permeable properties of the admixed liner. Laboratory and field tests such as compaction, hydraulic conductivity, density, water content for the soil-bentonite admixed liner were carried out. Quality control criteria for the best construction of the soil-bentonite admixed liner was suggested through laboratory and field test results.

• 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.

• Journal of the Korean Geotechnical Society
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• v.23 no.7
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• pp.47-55
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• 2007

In this study, applicability of electrical conductivity monitoring technique for containment barrier such as soil-bentonite wall was evaluated. Laboratory tests including permeability tests and column tests were performed to understand variations in electrical conductivity at different bentonite contents, hydraulic conductivities, and heavy metal concentrations. The electrical conductivity of compacted soil-bentonite mixtures was found to increase proportionally with bentonite content. Accordingly, the hydraulic conductivity of compacted soil-bentonite mixtures which decreases linearly with increasing bentonite content was found to have an inversely proportional relationship with the electrical conductivity. In column tests, electrical conductivity breakthrough curves and concentration breakthrough curves were simultaneously obtained. These results indicated that electrical conductivity measurement can be an effective means of detecting heavy metal transport at the desired locations within barriers and verifying possible contaminant leakage. Experimental results obtained from this study showed that the electrical conductivity measurement can be a promising tool for monitoring of containment barrier.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.2
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• pp.122-131
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• 2001

When mixed with lime, sand-bentonite mixture is characterized by considerable hydraulic properties similar to natural pozzolans and may therefore be increased in the strength of sand-bentonite mixture. The present study reports that results obtained in a series of laboratory tests carried out using particular mixing ratio of lime-sand-bentonite with the aim of investigating physical characteristics, permeability and strength. The results were compared and analyzed according to hydration time and lime content. Test results showed that increasing of strength and decreasing of permeability by proper lime content. Curing for longer periods increased unconfined compressive strength of mixture. Based on results of the falling head permeability test, mixtures of lime content 3%, 6% and 9% were satisfied in using as liner after 8-day curing periods.

• New & Renewable Energy
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• v.3 no.4
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• pp.38-46
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• 2007

In order to characterize the thermal conductivity and viscosity of grout materials used for backfilling ground heat exchangers, nine bentonite grouts and cement grouts being adapted in the United State have been considered in this study. The bentonite grouts indicate that the thermal conductivity and viscosity increase with the content of bentonite or filler (silica sand). In addition, material segregation can be observed when the viscosity of grout is relatively low. The saturated cement grouts appear to possess much higher thermal conductivity than the saturated bentonite grouts, and the reduction of thermal conductivity in the cement grouts after drying specimens is less than the case of the bentonite grouts. Maintaining the moisture content of grouts is a crucial factor in enhancing the efficiency of ground heat exchangers.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.529-532
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• 2007

In order to characterize the thermal conductivity and viscosity of grout materials used for backfilling ground heat exchangers, nine bentonite grouts and cement grouts being adapted in the United State have been considered in this study. The bentonite grouts indicate that the thermal conductivity and viscosity increase with the content of bentonite or filler (silica sand). In addition, material segregation can be observed when the viscosity of grout is relatively low. The saturated cement grouts appear to possess much higher thermal conductivity than the saturated bentonite grouts, and the reduction of thermal conductivity in the cement grouts after drying specimens is less than in case of the bentonite grouts. Maintaining the moisture content of grouts is a crucial factor in enhancing the efficiency of ground heat exchangers.

• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.1041-1048
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• 2021

An engineered barrier system (EBS) for the disposal of high-level radioactive waste (HLW) is composed of a disposal canister with spent fuel, a buffer material, a gap-filling material, and a backfill material. As the buffer is located in the empty space between the disposal canisters and the surrounding rock mass, it prevents the inflow of groundwater and retards the spill of radionuclides from the disposal canister. Due to the fact that the buffer gradually becomes saturated over a long time period, it is especially important to investigate its thermal-hydro-mechanical-chemical (THMC) properties considering variations of saturated condition. Therefore, this paper suggests a new method of measuring thermal conductivity and water suction for single compacted bentonite at various levels of saturation. This paper also highlights a convenient method of saturating compacted bentonite. The proposed method was verified with a previous method by comparing thermal conductivity and water suction with respect to water content. The relative error between the thermal conductivity and water suction values obtained through the proposed method and the previous method was determined as within 5% for compacted bentonite with a given water content.

• Journal of the Korean Chemical Society
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• v.21 no.5
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• pp.379-383
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• 1977

Since the organophilic bentonite disperses well in polymer matrix, a composite material of polymer and bentonite was studied for its mechanical properties. To increase the degree of dispersion and the bond in forces to the polymer matrix, bentonite, encapsulated by imidazoline, was used as a filler. Polyethylene powder of particle size of 100 mesh was used, and organophilic bentonite, so-called bentone, whose particle size was 250 mesh was also used in this experiment. V-type mixer was used for mixing and Banbury mixer was used for melt-blending. The sample specimen were made by heating the mixture in the plate press, and the specimen were formed as a sheet, exactly the same as the mold on the plate. Tensile strength, bending strength and compressive strength were studied specially. Tensile strength, elongation rate, bending strength and bending rate at constant pressure were decreased as the filler content increased. Compressive strength was increased as the filler content increased.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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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.

• KCID journal
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• v.5 no.1
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• pp.63-74
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• 1998

This study was performed to evaluate the hydraulic conductivity of sand-bentonite mixtures according to 8 kinds of the bentonite content using the reassembled air-entry permeameter. Results obtained are as follows: 1. The maximum dry density and optimum m