• Title/Summary/Keyword: 초유동 콘크리트

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Properties of Water Content Variances in Ultra High Flowing Concrete Before and After the Pumping Operation (현장적용 초유동 콘크리트의 펌프압송 전후 단위수량 변화 특성)

  • Kim, Kyoung-Min;Yoo, Jae-Kang;Shin, Hong-Cheol;Choi, Jong-Won
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.401-404
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    • 2006
  • This study is the part of the investigation of the state of the art in ultra high flowing concrete (UHFC), applied in practical field construction, in order to develop the technology for improving workability. This paper includes a brief introduction of water content variance properties in UHFC before and after the pumping operation. Test showed that water content in all parameters decreased after the pumping. This is due to the increase of an absorption ratio of coarse aggregate by the pressure of the pumping operation. thus decreasing the water content. Therefore it should be considered to find out the possibility, which can improve the workability, suffering from over viscosity by the lower water content, in field construction.

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The Influence of Fineness Modulus of Pine Aggregate and Grain Shape of Coarse Aggregate on the Properties of High Flowing Concrete (잔골재 조립률 및 굵은골재 입형이 초유동 콘크리트의 특성에 미치는 영향)

  • Jung Yong-Wook;Lee Seung-han;Yun Yong-Ho
    • Journal of the Korea Concrete Institute
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    • v.17 no.5 s.89
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    • pp.785-792
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    • 2005
  • This study is to examine the influence of defective grain shape of coarse aggregate and lowered fineness modulus of fine aggregate on the characteristics of high flowing concrete. The flow ability and compact ability of high flowing concrete was examined using fine aggregate, varying its fineness modulus to 2.0, 2.5, 3.0, and 3.5, and coarse aggregate with before and after grain shape improvement. Also the influence of fineness modulus of fine aggregate and grain shape of coarse aggregate on dispersion distance of particles of aggregate was examined by relatively comparing the dispersion distance between particles of aggregate. According to the experimental result, minimum porosity when mixing fine aggregate and coarse aggregate was shown in order of fineness modulus of fine aggregate, 3.0, 2.5, 2.0, 3.5, regardless of the improvement of grain shape. So when the fineness modulus is bigger or smaller than KS Standard $2.3\~3.1$, the porosity increased. When the spherical rate of the grain shape of coarse aggregate unproved from 0.69, a disk shape to 0.78 sphere shape, the rate of fine aggregate, which represents minimum porosity, decreased $6\%$ from $47\%\;to\;41\%$. The 28 days compressive strength according to fineness modulus of fine aggregate increased about 3 ma as the fineness modulus increased from 2.0 to 2,5, and 3.0. However, the 28 days compressive strength decreased about 9 ma at 3.5 fineness modulus as compared with 3.0 fineness modulus. The improvement of grain shape in coarse aggregate and increase of fineness modulus in fine aggregate made the flow ability, compact ability, and V-rod flowing time improve. Also the fineness modulus of fine aggregate increased the paste volume ratio when a higher value was used within the scope of KS Standard $2.3\~3.1$.

Properties of Superplasticized Ready Mixed Concrete for Heavily Reinforced Concrete Structure (철근배근이 복잡한 구조물에 타설하기 쉬운 초유동 레미콘 특성)

  • 조일호;신무섭;백일환;이건갑
    • Proceedings of the Korea Concrete Institute Conference
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    • 1997.04a
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    • pp.210-219
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    • 1997
  • This research which lays emphasis on ready mixed concrete standard 25-210~240kgf/$\textrm{cm}^2$ shows the influence caused by the ratio of ingredients of superplasticized concrete, and the flowing and strength development of mortar and concrete according to the ratio of ingredients. This research shows that flowability, compactability, and segregation resistivity are the best condition under the following ratio of ingredients: fly ash 30%, unit binders 490~510kg/$\textrm{m}^3$, unit weight of water 184~194kg/$\textrm{m}^3$, fine aggregate ratio 49~51%, and superplasticizer 1.1~1.5%. Following this ratio of ingredients, the reinforced concrete structures to need design strength 25-210~240kgf/$\textrm{cm}^2$ can apply to complicated constructions.

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The Selection of Optimal Mixing Proportion and Cost Analysis in the SFC (초유동 콘크리트의 최적배합 선정방법 및 경제성 분석)

  • Park, Chil-Lim;Kim, Moo-Han;Kwon, Yeong-Ho;Lee, Sang-Soo;Won, Cheol
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10a
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    • pp.262-268
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    • 1998
  • This research is to examine the selected method of optimal mixing proportion and cost analysis in the super flowing concrete. As confined water $ratio($\beta_p$)$ and K is introduced, itis to establish optimal mixing design of super flowing concrete according to the steps of paste, mortar and concrete. From paste and mortar test, it was led to $$\beta_p$$ and $K_p$satisfying the optimum condions depending on the kinds of binders. Then $$\beta_p$$ and $K_p$ is reflected to the mix condition of super flowing concrete. The result of test, the mix condition of super flowing concrete satisfied the quality performance of concrete with adjustment of additional rate of the superplasticizer. Besides, in case of design strength $350kg/\textrm{cm}^2$ of concrete, material cost in super flowing concrete is able to be reduced 5~16% in replacement of fly ash 30% in ordinary portland cement and slag cement.

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Flowability Evaluation of Binary and Ternary Blended of Ultra Flowing Self-Compacting Concrete (2성분계 및 3성분계 초유동 자기충전 콘크리트의 유동성 평가)

  • Choi, Yun-Wang;Jeon, Jun-Yong;Kim, Chung-Un;Jung, Jea-Guane;Jung, Woo-Young
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.485-488
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    • 2006
  • This research has evaluated flowability of ultra flowing self-compacting concrete, which is limitedly used for traditional building structures, in accordance with the first class regulations of Japan Society of Civil Engineering(JSCE) that can be applied to overcrowding-arrangement of bar, as a part of application methods that ultra flowing self-compacting concrete is applied to both precast and prestress bridge structures. The experimental results show that the flowability is acceptable in ternary blended among binary and ternary blended mixings, which satifies the first class regulation of JSCE. It is also concluded to use fly ash to increase viscosity of concrete in the case of segregation resistance because of low viscosity in the mixture of slag from blast furnace and limestone micropowder. Satisfying goals of every mixing after U-box self-compacting experiment, we conclude that ultra flowing self-compacting concrete is applicable to bridges and civil constructions of overcrowding arrangement of bar with evaluation of flowability of ultra flowing self-compacting concrete.

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Fluidity of Super Flow Concrete Using Recycled Coarse Aggregate (재생굵은골재를 사용한 초유동 콘크리트의 유동성)

  • Sung, Chan-Yong;Park, Il-Soon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.47 no.2
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    • pp.55-61
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    • 2005
  • This study was performed to evaluate fluidity of super flow concrete using recycled coarse aggregate. The unit weight was $2,246{\sim}2,344\;kg/m^3$, the unit weights of these concrete were decreased with increasing the content of fly ash and recycled coarse aggregate. The slump flow was $58{\sim}63\;cm$, the Box type passing was $3.4{\sim}6.8\;cm$, respectively. The L type compacting was excellent in the fly ash content $10\%\;and\;20\%$, but, it was showed in good in the fly ash content $30\%$. The super flow concretes using recycled coarse aggregate were improved by substitution in the range of less than the fly ash content $20\%$ and recycled coarse aggregate content $75\%$. This recycled coarse aggregate can be used for super flow concrete.

An Experimental Study on the Characteristics and Lateral Pressure of Super-Workable Concrete (초유동 콘트리트의 재료적 특성과 거푸집 측압에 관한 실험적 연구)

  • 이준구
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.42 no.1
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    • pp.83-91
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    • 2000
  • The purpose of this study is to estimate quantitatively lateral pressure of super-workable fresh concrete applied to form-work of prototype structures, such as tall wall, retaining wall and beam. As a result of this experiment, a function applicable to design a form work system and to predict lateral pressure curve is formulated . Super-workable concrete may be used for the structures reinforced with dense re-bar like box culvert to place concrete at a time, and this study for lateral pressure of super-workable concrete may be useful for form design.

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Strengths and Non-destruction Properties of Super Flow Concrete Using Recycled Coarse Aggregate (재생굵은골재를 사용한 초유동 콘크리트의 강도 및 비파괴 특성)

  • Sung, Chan-Yong
    • Journal of The Korean Society of Agricultural Engineers
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    • v.47 no.1
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    • pp.25-32
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    • 2005
  • This study was performed to evaluate strengths and non-destruction properties of super flow concrete using recycled coarse aggregate. At the curing age of 28 days, the compressive strength was 22.7-37.5 MPa, the splitting tensile strength was $2.65\~3.73$ MPa, the flexural strength was $5.78\~6.86$ MPa, the ultrasonic pulse velocity was $3,103\~3,480$ mis, the dynamic modulus of elasticity was $3.401{\times}104\~4.521{\times}104$MPa, respectively. The strengths, ultrasonic pulse velocity and dynamic modulus of elasticity of super flow concrete were decreased with increasing the content of recycled coarse aggregate. The super flow concretes using recycled coarse aggregate were improved by substitution in the range of less than the fly ash content 30010 and recycled coarse aggregate content $75\%$.

An Experimental Study on the Flowability of Super Flowing Concrete (초유동콘크리트의 유동특성에 관한 실험적 연구)

  • 권영호;이상수;박연동;김진근;박칠림
    • Proceedings of the Korea Concrete Institute Conference
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    • 1995.10a
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    • pp.1-7
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    • 1995
  • In this paper, we decribed the basic elements required for the practical usage of super flowing concrete. The flowability and filingability of fresh concrete was measured by using six different testing methods. Also, two actual size members were used for investigating characteristics of the hardened concrete through variious experiments. As the result of the experimentation, the developed super flowing concrete shown high flowability and fillingability good enough for the requirement. Furthermore, inner uniformity of the no-vibrated concrete was verified by testing distribution of aggregates and core cylinders. Therefore, quality control and workability of concrete can be secured by using the super flowing concrete even without vibrating However, it ha been felt that development of easy evaluation methods for the super flowing concrete is in need.

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