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An Experimental Study on Strength Properties of Concrete Using Blast-Furnace Slag Subjected to Freezing at Early Age (초기재령에서 동결을 받은 고로슬래그 콘크리트의 강도발현특성에 관한 실험적 연구)

  • Choi, Sung-Woo;Ban, Seong-Soo;Ryu, Deuk-Hyun;Choi, Bong-Joo
    • Journal of the Korea Concrete Institute
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    • v.15 no.1
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    • pp.43-51
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    • 2003

  • Recently, to consider financial and constructive aspect usage of Admixture such as Blast-Furnace Slag and Fly-Ash, are increased. Also the use of cold-weather-concrete is increased. Blast-Furnace Slag, a by-product of steel industry, have many advantage to reduce the heat of hydration, increase in ultimate strength and etc. But it also reduces early-age strength, so it is prevented from using of Blast-Furnace Slag at cold-weather-concrete. In this study, for the purpose of increasing usage of Blast-Furnace Slag at cold-weather-concrete, it is investigated the strength properties of concrete subjected to frost damage for the cause of early age curing. The factors of this experience to give early frost damaged were Freezing temperature(-1, -10, $-15^{\circ}C$), Early curing age(0, 12, 24, 48hour), Freezing times(0, 12, 24, 48hour). According to this study, if early curing is carried out before haying frost damage, the strength of concrete used admixture, subjected to frost damage, is recovered. And that properties are considered, the effect of using admixture like blast-furnace-slag, is very high

  • https://doi.org/10.4334/JKCI.2003.15.1.043 인용 PDF KSCI

The Quality of Crushed Sand by Dry Production Process and Its Influence on Properties of Concrete (건식공정으로 생산한 부순 모래의 품질 및 콘크리트 특성에 미치는 영향)

  • Park, Cho-Bum;Baek, Chul-Woo;Kim, Ho-Su;Ryu, Deuk-Hyun
    • Journal of the Korea Concrete Institute
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    • v.18 no.3 s.93
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    • pp.415-423
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    • 2006

  • As the shortage of natural & good quality aggregate for concrete, it is needed development of alternative aggregate. At the present time, the crushed sand is widely used among the alternation aggregate, and the usage of crushed sand will be increased more and more. Generally, crushed sud is produced with wet process in domestic, but some manufacturing companies which are handicapped with local restrict are produced by dry process. In this study, analyzing the facilities of dry crushed sand, the quality properties of dry crushed sand was done by Korean Industrial Standards. Based on the quality results of dry crushed sand, the experiment of concrete with the dry crushed sand which is substitute for sea sand was done. As the results of basic qualities, the amount of 0.08 mm sieve passing ratio was over KS criteria, and the fineness modulus was higher than sea sand, and the other physical properties of dry crushed sand was similar to sea sand. The results of concrete experiment, according to the substitutive ratio of dry crushed sand is increased, the slump and air content of concrete was decreased by increase of fine particles of dry crushed sand, and the unit weight content, compressive & tensile strength of concrete were increased on the contrary. The physical properties of concrete used dry crushed sand were showed same tendency without relation to W/B. Consequently, if the fine particle contents of dry crushed sand was lower, it is judged that dry crushed sand is no problem to use for concrete aggregate and the amount of usage will be increased.

  • https://doi.org/10.4334/JKCI.2006.18.3.415 인용 PDF KSCI

The challenge of hapatitis B virus

  • Samanta, Hinadri K.
    • The Microorganisms and Industry
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    • v.13 no.3
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    • pp.3-11
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    • 1987

  • Hepatitis B virus (HBV) is a very serious threat to public health in most of the developing countries of the world. It is estimated that around 300 million people worldwide are chronic carriers of this virus and will transmit the disease both vertically and horizontally. Infection by this virus may cause a wide range of clinical manifestations ranging from an asymptomatic infection to liver cirrhosis.

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