• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.687-692
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• 2002

The chemical shrinkage and the autogenous shrinkage have been determined experimentally for cement pastes incorporating different W/C ratio and different amount of the following addition: silica fume, fly ash and sand. The measurement method of the chemical shrinkage and autogenous shrinkage both were the volumetric technique. The silica fume has a effect of increasing the autogenous shrinkage while have a minor effect on the chemical shrinkage. The addition of fly-ash and sand both decreased the amount of chemical shrinkage and autogenous shrinkage.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.900-902
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• 1999

This paper deals with the interrupting characteristics of fuses element in different media of arc extinguisher. Aluminum hydro-oxide, boron nitride, silica and there size have been investigated here for their prospects as filling media in heavy current, high breaking capacity fuses. The result of these study are compared with those on silica sand at high current. This study demonstrates that silica sand is far superior filler in fuses for heavy current interrupting then the compound tested.

• Cement Symposium
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• s.49
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• pp.23-24
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• 2022

Wollastonite is a promising sustainable cement mineral which directly reacts with carbon dioxide to form calcium carbonate and silica gel. Due to the carbon dioxide reaction, it can be undoubtly one of materials for carbon capture, utilization, and storage. In this study, feasibility study for synthesizing the wolloastonite crystal using sand and waste glass was performed instead of using reactive but expensive silica fume for silica source.

• Journal of Korea Soil Environment Society
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• v.2 no.3
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• pp.49-57
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• 1997

Naturally-occurring iron minerals, goethite and magnetite, were used to catalyze hydrogen peroxide and initiate Fenton-like oxidation of silica sand contaminated with diesel, kerosene in batch systems. Reaction conditions were investigated by varying H$_2$0$_2$concentration(0%, 1%, 15%), initial contaminant concentration(0.2, 0.5, 1.0g diesel and kerosene/kg soil), and iron minerals(1, 5wt% magnetite or goethite). Contaminant degradations in silica sand-iron mineral-$H_2O$$_2$ systems were identified by determining total petroleum hydrocarbon(TPH) concentration. In case of silica sand contaminated with diesel(1g contaminan/kg soil with 5wt% magnetite) addition of 0%, 1%, 15% of $H_2O$$_2$showed 0%, 25%, and 60% of TPH reduction in 8 days, respectively When the mineral contents were varied from 1 to 5wt%, removal of contaminants increased by 16% for magnetite and 13.1% for goethite. The results from system contaminated by kerosene were similar to those of the diesel. Reaction of magnetite system was more aggressive than that of goethite system due to dissolution of iron and presence of iron(II) and iron(III); however, dissolved iron precipitated on the surface of iron mineral and seemed to cause reducing electron transfer activity on the surface and quenching $H_2$$O_2$. The system used goethite has better treatment efficiency due to less $H_2$$O_2$ consumption. Results of this study showed possible application of catalyzed $H_2$$O_2$ system to petroleum contaminated site without addition of iron source since natural soils generally contain iron minerals such as magnetite and goethite.

• Journal of the Korean GEO-environmental Society
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• v.11 no.9
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• pp.47-53
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• 2010

This study was made on the fact that the compressive strength characteristic of the recently developed alkali silica-sol chemical grout material was examined, whose grout material used for this study was designed to understand its strength property through the uniaxial compressive strength test(homo-gel, sand-gel), permeability test, deflection strength test, etc. In order to compare with the engineering characteristics regarding alkali silica-sol grout material and sodium silicate grout material. The uniaxial compressive strength of silica-sol grout material was identified to be increased more than 3~5 times than sodium silicate grout material at the early stage(within 72 hours). When comparing with the uniaxial compressive strengths of Sand-gel and Homo-gel at the material age of 28 days in case of silica-sol grouting material the strength of Sand-gel was measured to be about 1.3 times higher than Homo-gel. In case of silica-sol, it is assumed to have the property to exert high strength when it is actually grouted into the ground. As a result of permeability test it is judged that it is possible to apply the silica-sol to the site in the place requiring the water cut-off as the silica-sol. As a result of testing the strength at the material age of 28 days of grouting-use silica-sol showed more than 3 times' difference than the sodium silicate grouting material.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.118-125
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• 2017

In this study, we examined the bond performance of FRP Hybrid Bars. FRP Hybrid Bars are developed by wrapping glass fibers on the outside of deformed steel rebars to solve the corrosion problem. The surface of the FRP Hybrid Bars was coated with resin and silica sand to enhance its adhesion bonding performance with concrete. Various parameters, such as the resin type, viscosity, and size of the silica sand, were selected in order to find the optimal surface condition of the FRP Hybrid Bars. For the bonding test, FRP Hybrid Bars were embedded in a concrete block with a size of 200 mm3 and the maximum load and slip were measured at the interface between the FRP Hybrid Bar and concrete through the pull-out test. From the experimental results, the maximum load and bond strength were calculated as a function of each experimental variable and the resin type, viscosity and size of the silica sand giving rise to the optimal bond performance were evaluated. The maximum bond strength of the specimen using epoxy resin and No. 5 silica sand was about 35% higher than that of the deformed rebar.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.68-71
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• 2013

Reactive Powder Concrete (RPC) is an ultra high strength and high ductility cement-based composite material and has shown some promise as a new generation concrete in construction field. It is characterized by a silica fume-cement mixture with very low water-binder (w/b) ratio and very dense microstructure, which is formed using various powders such as cement, silica fume and very fine quartz sand (0.15~0.4mm) instead of ordinary coarse aggregate. However, the unit weight of cement in RPC is as high as 900~1,000 kg/㎥ due to the use of very fine sand instead of coarse aggregate, and a large volume of relatively expensive silica fume as a high reactivity pozzolan is also used, which is not produced in Korea and thus must be imported. Since the density of RPC has a heavy weight at 2.5~3.0 g/㎤. In this study, the modified RPC was made by the combination of ternary pozzolanic materials such as blast furnace slag and fly ash, silica fume in order to economically and practically feasible for Korea's situation. The fire resistance and structural behavior of the modified RPC exposed to high temperature were investigated.

• Journal of Korea Foundry Society
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• v.2 no.4
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• pp.2-8
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• 1982

The behavior of sand and mold at high temperatures was generally agreed to importantly affect the quality of castings made. By changing water content through 2,4,6 and 8%, and bentonite content through 5,7,9 and 11%, specimens have been made according to the respective composition. Specimens have been subjected to hot compressive strength and thermal expansion at 400, 600, 800 and $1000^{\circ}C$ respectively. The results obtained were as follows ; 1. At each temperature, thermal expansion decreased and hot compressive strength increased with the increase in water content. 2. After thermal expansion was peaked at approximately $1000^{\circ}C$ the contraction and maximum hot compressive strength appeared. 3. At each temperature, maximum hot compressive strength appeared 2%, 4,6% and 8% water content for 7%, 9% and 11% bentonite content respectively. 4. When 2% $H_2O$ was added, though bentonite content was increased, hot compressive strength did not rarely change. 5. Until the thermal expansion was completed the required time was 15-18 minutes at $400^{\circ}C$ and $600^{\circ}C$, and 10-13 minutes at $800^{\circ}C$. At $1000^{\circ}C$, the required time was 7-9 minutes in order to gain the maximum expansion, after that, contraction proceeded during 3-4 minutes before expansion was completed.

• Journal of Industrial Technology
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• v.15
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• pp.77-82
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• 1995

The experimental study is conducted to analyze the characteristics of concrete included silica fume. The workability of concrete is controled by the ratio of mixture, such as superplastcizer, based on the constant rates of sand and cement. It is concluded that the strength and the frectu Toughness of concrete with silica fume are very improved.

• Advances in concrete construction
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• v.5 no.1
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• pp.65-74
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• 2017

This study was focused on the use of partial replacement of cement with glass powder in high strength concrete and also copper slag as a partial replacement of coarse sand in concrete. The high strength concrete was prepared with different mineral admixtures like silica fume, fly ash and rice ash husk in different proportions. An experimental investigation has been carried to study about the effect of glass powder on high strength copper slag concrete. The range of glass powder was 10%, 15% and 20% as a replacement of cement. The range of copper slag was 0%, 20%, 40% and 60% as a replacement of natural sand. In addition to the different percentage of fly ash, silica fume, and rice husk ash 5% and 10% was also studied in copper slag concrete. Thus, a total of 51 cubes were casted and compressive strength test was performed on them. The result of the study shows that the value of average compressive strength of concrete after addition of 10%, 15% and 20% of glass powder are 70.47, 72.01 and 73.31 respectively. The value of average compressive strength after addition of 20%, 40% and 60% copper slag as a replacement of sand are 72.18, 74.38 and 73.08 respectively. The value of average compressive strength after addition of 5% and 10% fly ash as a replacement of cement are 71.56 and 73.22. The value of average compressive strength after addition of 5% and 10% silica fume as a replacement of cement are 72.33 and 73.53. The value of average compressive strength after addition of 5% and 10% rice husk ash as a replacement of cement are 72.86 and 69.49. At the level of 20% replacement of cement by glass powder meets maximum strength as compared to that of controlled concrete and copper slag high strength concrete.