• Composites Research
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• v.36 no.4
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• pp.275-280
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• 2023

Because polymer-based composites are lightweight and have excellent properties, their demand is growing rapidly as a way to fulfill properties that are difficult to achieve with a single material. As a result, there has been a lot of research on polymer nanocomposites, which are made by dispersing particles with a size of 1-100 nm in a polymer matrix. In addition, many nanocomposites using thermoplastic resins as matrix materials are being studied. In this study, poly(ethylene terephthalate) (PET)-based nanocomposites containing organic nanoclays modified with cetyltrimethylammonium bromide (CTAB) as interlayer materials were prepared. Among various nanoclays, vermiculite (VMT) has been studied to increase the mechanical and thermal properties of polymeric materials due to its low cost, abundant reserves and unique properties. However, the strong interlayer bonding of VMT has limited its utilization due to its poor exfoliation and dispersion performance within polymer matrices. In this study, the mechanical properties of the VMT content were confirmed by tensile tests, the dispersion of VMT particles in the PET matrix was evaluated by TEM cross-sectional images, and the nitrogen gas barrier properties were evaluated.

• Journal of the Mineralogical Society of Korea
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• v.30 no.1
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• pp.11-19
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• 2017

Reddish brown clay-silt sediments covered granitoid weathering crust in the Jangdongri area, Naju, Korea. Mineralogical and geochemical properties of the ~2 m sediment section were investigated. The sediments were composed mainly of quartz (50%) and clay minerals (45%) with minor contents of K-feldspar, goethite, hematite, and gibbsite. The clay minerals were illite, illite-smectite mixed-layers, vermiculite, hydroxy-Al vermiculite, kaolinite, and halloysite. Mineral composition varied little through the section with the minor upward enrichment of plagioclase and chlorite. Abundant illitic clay minerals indicated the remote source of the sediments because clays derived by granite weathering in Korea were dominated by kaolin minerals. A comparison with the mineral composition of Asian dust (Hwangsa) suggested that plagioclase and K-feldspar disappeared by chemical weathering after deposition, resulting in the quartz and clay-rich sediments. Plagioclase and chlorite altered to kaolin and vermiculite, respectively. Goethite and hematite derived by the weathering of iron-bearing minerals stained the sediment to reddish brown color. The mineralogical and geochemical properties of the reddish brown clay-silt sediments were consistent with those of eolian deposits identified in Korea, supporting eolian origin of the Jangdongri sediments, requiring future confirmation including age dating and isotopic analysis.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.3
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• pp.217-222
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• 2009

This study was conducted to search possibilities of the use of sludge from waterworks industry in the manufacturing of red clay bricks. Different compositions of the sludge were added into the raw materials of the bricks and required engineering characteristics of the manufactured bricks were examined. Compressive strength, plasticity, and surface absorption of the recycled bricks were analyzed and were compared with the bricks quality standard rules and regulation for quality assurance of the product. Compressive strength of the bricks made in a ratio 75% clay, 5% sludge and 20% silica was found 261.3 $kg_f/cm^3$ and that was comparable with first grade bricks standard. Compressive strength of the bricks made in a ratio 70% clay, 10% sludge, and 20% silica was found 249.9 $kg_f/cm^3$ while it was decreased to 217.3 $kg_f/cm^3$ when bricks were made in a ratio 65% clay, 15% sludge and 20% silica. However, these values of compressive strength were in agreement with the bricks quality standard. Surface absorption of the bricks made by the mixing of 20% silica with varying amount of sludge, i.e., 5%, 10%, and 20% was found 10%, 9.65% and 10.92% respectively. These values satisfied the quality standard of bricks of grade 1 and 2. Recycling of proper amount of sludge in bricks making could produce bricks of high engineering characteristics.

• Nuclear Engineering and Technology
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• v.26 no.1
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• pp.54-62
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• 1994

The hydraulic properties of domestic natural clay/crushed rock mixture suggested as a candidate backfill material for the low and intermediate level waste repository were investigated. The dry density-water content relationship was studied to define an optimum water content that gives a maximum attainable dry density at constant compaction pressure. The hydraulic conductivities of clay/crushed rock mixture as a function of clay content were also measured. As the clay content decreased, the maximum attainable dry density increased and the optimum water content became more distinct. However the attainable density is not significantly sensitive to water content. The hydraulic conductivities of the mixture increased from 5 $\times$ 10$^{-12}$ m/s to 7 $\times$ 10$^{-10}$ m/s with clay content decreasing from 100 wt.% to 25 wt.% at dry density of 1.2 Mg/㎥. In case of dry density of 1.5 Mg/㎥, they maintain the lower values of 5 $\times$ 10$^{-12}$ m/s even at 25 wt.% clay content. The concept of effective clay dry density was suggested to estimate the hydraulic conductivity of the mixture. It was shown that the effective clay dry density concept can explain welt the hydraulic conductivities of the mixtures with various dry density and crushed rock content.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.13-23
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• 2008

The triaxial compression tests and consolidation tests using NaCl solution and leachates as substitute pore (or saturated) water in samples were carried out to find out the behavior characteristics of strength, deformation and permeability coefficient of contaminated clay. Also, the chemical property analysis on the clay samples using scanning electron microscope and energy dispersive x-ray spectrometer were involved. The magnitudes of composition ratio were shown in the order of O, C, Si, Al, and Fe as a result of chemical composition analysis for clay samples. Besides, as the results of triaxial compression tests and consolidation tests, the shear strength, compression and permeability properties were increased with increasing in the concentration of contaminant (NaCl). It may be considered that these circumstances be caused by the changes of soil structure to flocculent structure due to the decrease in the thickness of diffuse double layer with increasing in the concentration of electrolyte. MT3D model was also using to grasp the procedures that the groundwater may be contaminated by the leachates permeated through the clay liner. The results of contaminant transport analysis showed a tendency that the predicted concentration of groundwater was higher with increasing in the initial concentration of $Cl^-$ ion and increased as a nonlinear curves with time. The transportation distance calculated by the use of regression equation between the distance from contaminant source and the concentration of $Cl^-$ ion was increased with increasing the initial concentration.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1992.08a
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• pp.188-191
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• 1992

최근 해양공간의 이용 및 개발과 관련해서 하구역이나 연안해역의 개발이 활발하게 진행됨에 따라 연안해양환경의 예측과 제어에 관한 기술 개발이 중요한 과제로 대두되고 있다. 하구역이나 연안해역에 분포하는 물질 가운데 상당부분이 점토나 실트와 같은 점착성토사와 유기성 현탁입자로 구성되어 있다.(중략)

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2018.10a
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• pp.252-252
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• 2018

• Journal of Soil and Groundwater Environment
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• v.14 no.3
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• pp.47-56
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• 2009

This is a study about how the increase of strength is changed when ground improvement material is mixed with either coastal clay or sandy soil. The ground improvement material was made from mixing a certain proportion of the slag which is by-products generated by smelting the iron ore and the paper fly ash which is formed by bumping up the paper. The ground improvement material was added to coastal soil and sandy soil each. And then according to ratio of water contents, number of curing days and ratio of mixture, specimen for uniaxial compression test was made. The change of uniaxial compression strength and the generated substances was analyzed while the specimen is being cured for 28days. The result of analysis shows that the strength of coastal clay was increased about eleven times more than that of sandy soil. This means that ettringite reaction by ground improvement material becomes more distinctive in the coastal clay than in the sandy soil.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1C
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• pp.7-15
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• 2010

In case that the seepage of contaminants into the subsurface has been generated from the waste impoundment by demage of geomembrane liner, it is necessary to repair the leaks of geomembrane liner for minimizing the environmental contamination by electrophoresis method. However, when electrophoresis method is applied to leachate electrolyte system, the phenomenon of clay particles flocculation would be accelerated by the interaction between clay particles and specific chemicals in leachate. In addition, the gravitational settling behaviour would be induced superior to the electrophoretic migration behaviour. Eventually, the limitations of field applicability for using the electrophoresis method are appeared. Therefore, 1-D enhanced electrophoresis method is conducted to prevent the clay flocculation and accelerate the migration of clay particles separately. After the 1-D enhanced electrophoresis experiment, we can get the results that the deflocculation effect of clay particles is increased by electrical repulsion of polymer, which adsorbed in clay particle edge, in case of using PAA dispersing agent.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.317-328
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• 2019

In this work, we investigated clay and raw materials from China (black clay, red clay, white clay) and Korea (Cheonan clay, Obu clay) used for the manufacture of porcelain products. According to chemical analysis results, feldspar components containing CaO, K₂O, Na₂O and quartz are found in clay materials besides primary clay such as kaollinte, for the clay materials from Korea, which is found more in clay materials from Korea than from China. For the Fe₂O₃ content, governing whiteness of porcelain products, more iron oxide (> 5 %) is found in Korean clays (Cheonan clay, obu clay, red clay) compared to those form China (black, white clay). Through X-ray diffraction analysis, kaolinite and Halloysite are found to be main phases for all the raw materials and second phases such as quartz and pyrophyllite are found. Using these clay materials, raw materials for porcelain products were produced, and the physicochemical properties were investigated for sintered samples. Absorption rate is in order of Baekja-A < Baekja-B < Yeonbuncheong < Jinbuncheong < Cheongja, and the sample, sintered at 1250℃ in reductive atmosphere, exhibits the lowest absorption rate. Comparing the color of the sintered samples, the samples sintered in oxidative atmosphere (L^* value: 86~95 %) show higher whiteness value than those sintered in reductive atmosphere (L^* value: 81~93 %). For the Cheongja and Buncheong, the samples sintered in reductive atmosphre shows higher whiteness, L^* values, and low a^*/b^* value, which is due to reduction of iron oxide (Fe₂O₃).