• Title/Summary/Keyword: furnace

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Characterization of fine lightweight aggregates sintered at floating state using by vertical furnace (수직로에서 부유 소성된 경량 세골재의 특성)

  • Kang, Seung-Gu
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.18 no.6
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    • pp.258-263
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    • 2008
  • The fine aggregates of below 2 mm size was fabricated using by the vertical furnace in which the aggregates could be sintered at floating state and its physical properties were analyzed. The liquid formed at the surface of specimens sintered at $1200{\sim}l300^{\circ}C$ induced a gas in core to expand so the denser shell and porous core could be produced. The C series specimen fabricated by crushing an extruded body had an irregular shape and sharp edges but those became spheroidized by bloating due to gas expansion inside. The fine aggregates fabricated in this study was as light as floating in the water and had an apparent density of $0.68{\sim}1.08$. The absorption rate was proportioned to a porosity showing that the pores in core was not closed completely. The properties of fine aggregates fabricated in vertical furnace were similar with those of in an electric muffle furnace but the sticking-together phenomenon by surface fusion was not occurred in the vertical furnace. The aggregates fabricated in this study had a little lower impact resistance than that of natural aggregate but satisfied the unit volume weight standard specified in KS.

Strength Development and Freeze-Thaw Resistance of Concrete Incorporating High Volume Blast-Furnace Slag Subjected to Initial Frost Damage (초기동해를 받은 고로슬래그 다량 혼입 콘크리트의 강도발현 및 동결융해 저항성)

  • Koh, Kyung-Taek;Ryu, Gum-Sung
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.6 no.3
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    • pp.79-87
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    • 2011
  • Concrete incorporating high volume blast-furnace slag placed in cold weather regions might be in danger of initial frost damage because dependently on the mix proportions, the setting and the hardening would be remarkably delayed. Therefore, this study investigated to effect of the degree of frost on the strength development and the resistance to freezing and thawing of the concrete incorporating blast-furnace slag when being subjected to freeze at early age. As the experimental results, the concrete incorporating blast-furnace slag attacked by initial frost damage showed the remarkable reduction of both the compressive strength development and the resistance to freezing and thawing. Especially, the resistance to freezing-thawing of the concrete incorporating high volume blast-furnace slag became much lower than that of the normal concrete.

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Feasibility Analysis of Rapid Quality Evaluation Method for Blast Furnace Slag Using Hydrometer (Hydrometer를 이용한 고로슬래그 미분말의 분말도 품질 신속평가 가능성 분석)

  • Han, Cheon-Goo;Joo, Eun-Hui
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.6 no.1
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    • pp.43-49
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    • 2018
  • The aim of the research is to analyze the feasibility of rapid quality evaluation method for blast furnace slag using hydrometer based on the former research of the prediction method for concrete compressive strength using hydrometer. Using this method, it is expected to provide a new application for blast furnace slag quality evaluation easily and rapidly during the receiving inspection. According to the experimental results, the settling time period of hydrometer was delayed with increased fineness of blast furnace slag. By using the regression equation of y = 198 120 x - 193 936(R=0.9398) obtained from the correlation between density of suspension at three minutes and fineness, it was possible to evaluate the quality of blast furnace slag fineness rapidly. Therefore, for ready-mixed concrete receiving inspection, the suggested method can be used as a cheap, a simple, and a rapid inspection method.

The Effect of Combinations of Electric Arc Furnace Slag and Lime Stone aggregates on Engineering Properties of Ultra High Strength Concrete with 80MPa (전기로 산화슬래그 잔골재와 석회암 골재의 조합사용이 80MPa급 초고강도 콘크리트의 공학적 특성에 미치는 영향)

  • Han, Min-Cheol;Moon, Byeong-Yong
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.5 no.3
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    • pp.253-260
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    • 2017
  • The aim of research is to investigate various physical properties of ultra high strength concrete of 80MPa class using a combination of limestone aggregate and electronic arc furnace oxidizing slag aggregate. For aggregate combinations, granite and limestone are used for coarse aggregate, granite and limestone are also used for fine aggregate. And also, limestone fine aggregate is replaced by electronic arc furnace oxidizing slag aggregate of 25% and 50%. Test results indicated that flowability and compressive strength increased when limestone fine aggregate was used compared to that using granite fine aggregate due to higher modulus of elasticity by limestone. Also substitution of electronic arc furnace oxidizing slag aggregate resulted in a decrease of compressive strength slightly. It is found that the use of electronic arc furnace oxidizing slag aggregate and limestone aggregate would be favorable for reducing the autogenous shrinkage by as much as 9~25%.

Study of Fundamental Properties of Latex-Modified Concrete Using Blast-furnace Slag (고로(高爐)슬래그 미분말(微粉末)을 사용(使用)한 라텍스개질(改質) 콘크리트의 기초물성(基礎物性) 연구(硏究))

  • Hong, Chang-Woo;Jeong, Won-Kyong;Kim, Kyeong-Jin
    • Resources Recycling
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    • v.15 no.2 s.70
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    • pp.10-17
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    • 2006
  • The purpose of this study was to evaluate the effects of blast-furnace slag on strength development and durability of latex-modified concrete (LMC) and ordinary portland cement concrete as slag contents. Main experimental variables were performed latex contents (0%, 10%, 15%) and slag contents (0%, 30%). The compressive and flexural strengths, chloride-ion rapid permeability and chemical attacks resistance were measured to analyze the characteristic of the developed LMC and BS-LMC(latex-modified concrete added blast-furnace slag) on hardened concrete. The test results showed that compressive and flexural strength of BS-LMC increased as the slag contents increased from 0% to 30% at the long term of curing. It considers blast furnace slag used when latex content was up to 10%. The permeability resistance of BS-LMC(latex 10%, blast 30%) was extremely good at the curing time 90 days. Also. the effects of added blast furnace slag on OPC and LMC were increased on the permeability and chemical attacks resistance.

Improvement of Early Strength of Blast-Furnace Slag Blended Cement at Low Temperature (고로 슬래그 시멘트의 저온 조기 강도 증진)

  • 장복기;임용무;김윤주
    • Journal of the Korean Ceramic Society
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    • v.36 no.2
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    • pp.130-135
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    • 1999
  • The enhanced slag fineness and the batch water of low water-to-cement ratio(W/C) were employed in order to improve the early strength of blast-furnace slag blended cement at low temperature. A grinding aid was used to grind the blast-furnace slag into the fineness of 6,280$\textrm{cm}^2$/g (Blaine), and this fine slag was then homogeneously mixed with the ordinary Portland cement to produce the blast-furnace slag blended cement containing 40% slag by weight composition. On the other hand, the batch water could be reduced from W/C=0.50 (KS L 5105) to W/C=0.33 through a commercial, naphthalene type superplasticizer. Through the method mentioned above, the early strength of the blast-furnace slag blended cement at low temperature could be enhanced even somewhat higher than the Portland cement strength. And the microsturcture of the cement was studied by both the pore structure analysis and the A.C. impedance measurement.

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