• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.687-690
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• 2004

The discharge of sewage sludge ash that is rapidly increasing in Korea. The utilization of sewage sludge ash would contribute to the elimination of an environmental problem and to the development of new high-performance materials. So the paper is focused on an experimental study in order to investigate the utilization of sewage sludge ash as the construction materials. It achieves leaching test, chemical composition and compressive strength test. As a result of tests, the sewage sludge ash has sufficient potential for use of pozzolanic raw material. However. it is judged to be available to construction material if research is continuously gone.

• Journal of Magnetics
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• 제18권3호
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• pp.365-369
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• 2013

Coal ash is known to contain a noticeable amount of valuable elements, including transition metals and lanthanides. Therefore it is quite actual problem to extract them for metallurgy and other applications. This paper presents the results of high gradient magnetic and mechanical separation, microscopy, element analyses and optical spectroscopy of brown coal ash taken from the combustion camera and chimney-stalk of Angren thermal power station. The separated magnetic fraction was 3.4 wt.%, where the content of Fe in ferrospheres increased to 58 wt.%. The highest contents of Fe and rare earth elements were found in the fine fractions of $50-100{\mu}m$. Optical absorption spectroscopy of water solutions of the magnetic fractions revealed $Fe^{2+}$ and $Fe^{3+}$ ions in the ratio of ~1:1. The separated coal ash could be used for cleaning of technological liquid waste by means of the high gradient magnetic field.

• 한국환경과학회지
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• 제15권2호
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• pp.185-191
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• 2006

In this paper, removal time of side form from concrete using OPC(ordinary Portland cement) and FAC(fly ash cement) are proposed by appling logistic model, which evaluates the strength development of concrete with maturity. W/B, types of cement and curing temperatures are adapted as test parameters. The estimation of strength development by logistic model has a good agreement between calculated values and measured ones. As for the removal times of form works suggested in this paper, as W/8 increases, curing temperature decreases and fly ash is used, removal time of side form is prolonged. Removal time of form from concrete using OPC suggested in this paper is shorter $2.5\~3.5$ days than those of KASS-5 (Korean Architectural Standard Specifications-5) in the range of over $20^{\circ}C$. And in the range of $10\~20^{\circ}C$ removal time of form is shorter than that of KASS-5 by as much as $4\~4.5$ days. The use of FAC results in an increase in removal time of form compared to that of OPC by about 1 day.

• 한국건설순환자원학회논문집
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• 제8권4호
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• pp.596-603
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• 2020

본 논문에서는 화력발전소 산업부산물인 바텀애시의 활용성을 증대시키기 위한 실험연구를 수행하였다. 본 연구에서는 바텀애시를 잔골재로 설정하였으며, 골재 특성 파악을 위한 실험을 수행하였다. 부순 잔골재의 25, 50, 75 및 100%를 바텀애시로 치환하여 바텀애시를 혼입한 콘크리트를 제작하였으며, 재료특성으로서 단위중량, 초음파속도, 압축강도 및 열전도율 실험을 수행하여 결과를 도출하였다. 한편, 바텀애시는 포졸란재료로써 가능성이 있으며, 재령 28일과 91일로 구분하여 양생기간에 따른 영향을 파악하였다. 측정된 실험결과를 토대로 다공질 및 경량 특성을 갖는 바텀애시를 잔골재로 사용한 콘크리트의 열전도율 특성과 단위중량, 초음파속도 및 압축강도와의 상관관계를 제시하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.753-756
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• 2005

Recently, the alkali activation of Fly-ash has become a significant field of research because it is possible to use these materials having highly chemical reaction property. Also, the product does not generate CO2 gas, unlike ordinary Portland cement(O.P.C). Therefore, the purpose of this paper is to design for improving mechanical and chemical properties using Fly-ash and Meta-kaolin. And additive(CaO) affected to control the strength behaviors and shrinkage rate.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.15-18
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• 1998

In this paper, the properties of high performance concrete with fly ash and expansive additives are investigated. According to the experimental results, when 10% of fly ash and 5% of expansive additives are mixed in concrete mixture, the improvement of the quality in the side of the fluidity, strength and the prevent of the crack caused by drying-shringkage can be accomplished.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1991년도 가을 학술발표회 논문집
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• pp.99-106
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• 1991

Result of an experimental study on the manufacture, the mechanical properties and waterightness of pitch-based carbon fiber reinforced fly ash.cement composites are presented in this paper. The carbon fiber reinforced fly ash.cement composites using early strength cement, silica powder and a small amount of stylene butadiene rubber latex are prepared with carbon fiber, foaming agents and mixing conditions. As a result, the mechanical and plysical properties such as compresive, tensile and flectural strengths, watertightness and cement composites are improved by using a small amount of stylene butadiene rubber latex.

• 펄프종이기술
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• 제33권2호
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• pp.58-67
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• 2001

MOW (Mixed Office Waste) mainly consisted of photocopied paper is being recycled to produce tissue or fine paper products. Toner particles that are fused and set on paper surface in photocopying process turns into large and plate-shaped particles after repulping which prevents them to be removed effectively in flotation deinking. The immediate purpose of this study is to find the effective deinking technology that increases the recycling potential of photocopied papers for manufacturing tissue and fine paper products. In this study the effects of pulping temperature and the type of hydrophobic groups of nonionic surfactants on the deinking efficiency of photocopied paper has been investigated. Particle size distribution of the toner particles after pulping and flotation, brightness, yield and ash removal were investigated. The size of toner particles after pulping increased as the pulping temperature was increased. When pulping at the low temperature finer toner particles were generated, however, greater amount of toner particles was found to attach to the fiber. When the pulping temperature was greater than Tg of the toner, the amount of coarse hairy particles increased. When nonionic surfactants with a double bond in hydrophobic groups were used, toner removal efficiency, brightness and ash removal were increased. As the addition level of surfactant was increased, yield decreased rather sharply without improving brightness.

• KEPCO Journal on Electric Power and Energy
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• 제2권3호
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• pp.437-445
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• 2016

This paper discussed the effect of ammonia concentration adsorbed on fly ash for the ammonia emission as AAFA (Ammonia Adsorbed Fly Ash) produced from coal fired plants due to operation of NOx reduction technologies was landfilled with distilled or sea water at closed and open systems, respectively. Ammonia bisulfate and sulfates adsorbed on fly ash is highly water soluble. The pH of ammonium bisulfate and sulfate solution had significant effect on ammonia odor emission. The effect of temperature on ammonia odor emission from mixture was less than pH, the rate of ammonia emission increased with increased temperature when the pH conditions were kept at constant. Since AAFA increases the pH of solution substantially, $NH_3$ in the ash can release the ammonia order unless it is present at low concentration. $NH_4{^+}$ ion is unstable in fly ash and water mixtures of high pH at open system, which is changed to nitrite or nitrate and then released as ammonia gas. The proper conditions for < 20 ppm of ammonia concentration released from the AAFAs landfilled in ash pond were explored using an open system with sea water. It was therefore proposed that optimal operation to collect AAFA of less than 168 ppm ammonia at the electrostatic precipitator were controlled to ammonia slip with less than 5 ppm at SCR/SNCR installations, and, ammonia odor released from mixture of fly ash of 168 ppm ammonia with sea water under open system has about 20 ppm.

• 한국지반환경공학회 논문집
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• 제4권4호
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• pp.25-34
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• 2003

본 논문에서는 일련의 실내실험을 통하여 하수회의 기본특성, 다짐, 압축강도, 압밀, 투수 및 CBR 특성을 분석하여 폐기물 매립장의 차수재 및 복토재 등의 건설재료로서 하수슬러지 소각재의 활용방안을 연구하였다. 특히, 하수슬러지 소각재의 치환률을 5, 10, 15, 20, 25, 30%로 변화시키면서 점토벽돌을 제작하여 품질시험을 실시하였다. 하수슬러지 소각재의 투수특성을 확보하기 위하여 혼합재로서 벤토나이트와 소석회를 사용하였다. 실험결과, 벤토나이트 혼합비가 증가함에 따라 투수계수는 감소하며 차수재로 사용가능한 투수계수가 $1{\times}10^{-7}cm/sec$ 이하로 되는 벤토나이트의 혼합비는 20% 정도로 나타났다. 일축압축시험결과 하수슬러지 소각재는 복토재의 일축압축강도 기준을 만족하는 것으로 평가되었다. 점토벽돌에 대한 품질시험 결과 하수슬러지 소각재의 치환률이 증가함에 따라 압축강도는 감소하였으며, 3종 점토벽돌의 품질기준을 만족하는 하수회의 최대치환률은 15% 정도로 나타났다.