• Journal of Industrial Technology
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• v.31 no.B
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• pp.27-36
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• 2011

In this paper, the applicability of cement grout has been studied as an alternative to bentonite grout for backfill ground heat exchangers. To provide an optimal mixture design, the thermal conductivity of cement grout and bentonite grout with various mixture ratios were experimentally evaluated and compared. Numerical analyses using Fluent(FVM program) were applied to compare the thermal transfer efficiency of the cement grout with that of the bentonite grout used in the construction. Also the effective ground thermal conductivity was measured by In-situ thermal response test. The results showed that the thermal efficiency of the cement grout was better than the bentonite grout. Consequently, the cement grout could be an alternative with more thermal efficiency to bentonite grout for ground heat exchangers.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.168-171
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• 2001

Organobentonite modified with hexadecyltrimethylammonium (HDTMA) was used to quantify an adsorption of heavy metals. Based on preliminary experiments, optimal soil/solution ratio, a range of pH, and electrolyte were selected. Adsorption experiments of cadmium and lead were conducted to quantify an adsorption selectivity to bentonite and organobentonite. Adsorption of cadmium and lead to bentonite was increased with increasing a soil/solution ratio. Adsorption of cadmium and lead to bentonite was increased with increasing a soil/solution ratio. Adsorptions of heavy metal to organobentonite were slightly reduced relative to bentonite. This study used the principle of hard-soft-acid-base (HBAB) to interpretate an adsorption mechanism. Because of competition between cadmium and lead. adsorption of cadmium and lead was reduced in mixture of heavy metals. Adsorption selectivity.

• 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.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.445-452
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• 2001

Generally, OPC(ordinary portland cement) is used for grouting in Korea, and bentonite has usually been added to prevent the deposition of cement particles. The dispersion of CB(cement bentonite) grout is influenced by variable factors i.e. water to cement ratio, particle size of cement, kind of bentonite, adding volume, methods of adding, viscosity of CB grout materials and curdling time. Among variable factors, the viscosity of CB grout materials is influenced by the dispersion, and dispersion is improved as increasing the mixing speed. In this paper, described a suitable mixing speed of the High Speed Mixer in field, engineering characteristics of CB grout materials vary with the water to cement ratio and the mixing speed as well as confirming the state of dispersion.

• Journal of the Korean Solar Energy Society
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• v.33 no.1
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• pp.66-72
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• 2013

In this study, the thermal conductive characteristics and basic properties of the nine commercial products of bentonite grouts were studied. Six of the nine products for ground heat exchanger systems are imported and others for civil engineering are domestic. The thermal conductivities of all bentonite products are nearly similar among products. The free swell indexes, viscosities and filter losses of the ground heat exchanger grouts are lower than those of the civil engineering ones. These characteristics seem to increase of the fluidity to fill the bentonite slurry to bore-hall perfectly, rather than to prevent underground water penetration. Thus, the mixtures of bentonites and sands are recommended for high thermal conduction grouts.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.713-718
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• 2006

This paper concerns the measurement of thermal conductivity of grouting materials for ground loop heat exchanger. A thermal conductivity meter, QTM-500 based on modified transient hot wire method was used to measure the thermal conductivity of neat bentonite and mixtures of bentonite and various additives. Relative to the total mixture mass, as the percent additive was increased the mixture thermal conductivity increased. For the bentonite-silica sand mixtures, the higher density of the sand particles resulted in much higher mixture thermal conductivity.

• 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.

• Nuclear Engineering and Technology
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• v.30 no.1
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• pp.1-7
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• 1998

Effects of pH, bentonite and Portland cement on the leaching of the simulated waste glass were investigated. The simulated waste glass showed the low leach rate in the neutral pH region, while the leach rate in both acidic and alkaline regions increased. Addition of bentonite to the leachant enhanced the leaching of the waste glass. When the waste glass was leached at 72$^{\circ}C$ for 36 days in the ground water with gel state Na-bentonite, approximately 2.2${\mu}{\textrm}{m}$ of the surface was corroded out and the large amount of Ti, Nd, and Zr was observed on the surface. The amount of B leached from the simulated waste glass in the presence of domestic bentonite was about three times higher than that in the presence of Aldrich bentonite as well as Portland cement.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.777-782
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• 2013

In order to further reduce the sulfur content in liquid hydrocarbon fuels, a desulfurization process by adsorption for removing dimethyl sulfide (DMS) and propylmercaptan (PM) was investigated. Bentonite adsorbents modified by $CuCl_2$ for the desulfurization of model oil was investigated. The results indicated that the modified bentonite adsorbents were effective for adsorption of DMS and PM. The bentonite adsorbents were characterized by X-ray diffraction (XRD) and thermal analysis (TGA). The acidity was measured by FT-IR spectroscopy. Several factors that influence the desulfurization capability, including loading and calcination temperature, were studied. The maximum sulfur adsorption capacity was obtained at a Cu(II) loading of 15 wt %, and the optimum calcination temperature was $150^{\circ}C$. Spectral shifts of the ${\nu}$(C-S) and ${\nu}$(Cu-S) vibrations of the complex compound obtained by the reaction of $CuCl_2$ and DMS were measured with the Raman spectrum. On the basis of complex adsorption reaction and hybrid orbital theory, the adsorption on modified bentonite occurred via multilayer intermolecular forces and S-M (${\sigma}$) bonds.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.533-544
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• 2008

To obtain the physical properties of grout materials, that is the thermal conductivity and viscosity, which are 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 show that the thermal conductivity and viscosity increase with the content of bentonite or filler (silica sand). 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. To investigate the performance of cement grouts, fifteen samples were prepared by varying the water/cement ratio and the amount of sand and bentonite added into the cement mortar. Maintaining the moisture content of grouts is a crucial factor in enhancing the efficiency of ground heat exchangers.