• 제목/요약/키워드: Bleeding content

검색결과 109건 처리시간 0.026초

콘크리트의 블리딩에 미치는 혼화제의 영향 (Influence of Chemical Admixture on Bleeding of Concrete)

  • 김은호;황인성;손유신;김규용;한천구
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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    • pp.339-342
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    • 2003
  • This study is intended to investigate the influence of chemical admixture on bleeding of concrete. According to the results, the amount of bleeding with elapse of time does not make much difference in the case of naphthalene type water reducing agent(RN), Naphthalene type high performance water reducing agent(HN) and Melamine type high performance water reducing agent(HM), but it is largest in the case of Polycarbonic acid type high performance water reducing agent(HP). Bleeding speed also is highest in the case of HP in comparison with other chemical admixture. This prove that high performance water reducing agent like HP has little effect on fluidity of concrete, but influences the amount of bleeding more greatly, instead. As properties of hardened concrete, compressive strength makes no difference in the case of RN, HN and HM, but on the other hand, it increases in the case of HP due to a decrease of air content and the large amount of bleeding.

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굳지 않은 경량골재 콘크리트의 공기량, 유동성 및 블리딩 특성 (Air Content, Workability and Bleeding Characteristics of Fresh Lightweight Aggregate Concrete)

  • 심재일;양근혁
    • 콘크리트학회논문집
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    • 제22권4호
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    • pp.559-566
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    • 2010
  • 굳지 않은 경량골재 콘크리트의 다양한 특성에 대한 경량굵은골재 최대크기와 천연모래 치환율의 영향을 평가하기 위해 15배합의 경량골재 콘크리트가 배합되었다. 또한 굳지 않은 경량골재 콘크리트의 유동특성에 영향을 줄 수 있는 경량골재의 내부구조와 공극의 분포 및 시간에 따른 흡수 특성 등이 측정되었다. 실험 결과 경량골재 콘크리트의 초기 슬럼프는 천연 모래 치환율이 증가할수록 감소하였으며, 전경량 콘크리트의 슬럼프는 배합 후 30~60분 사이에 초기 슬럼프의 80%가 감소하였다. 경량골재 콘크리트의 공기량과 블리딩 량은 경량굵은골재 최대크기와 천연 모래 치환율에 중요한 영향을 받았다. 경험식인 ACI 211과 콘크리트표준시방서는 경량골재 콘크리트의 공기량을 과소평가 하였으며, 천연 모래 치환율의 감소할수록 그 과소평가 정도는 증가하였다. 이 연구에 의해 제안된 경량골재 콘크리트의 공기량과 블리딩율에 대한 예측모델은 실험 결과와 잘 일치하였다.

고성능감수제 종류에 따른 유도화콘크리트의 Bleeding특성 (A Study on the Bleeding Property of Flowed Concrete Due to Different Types of High Range Water Reducing Admixtures)

  • 김기수;하재담;김동석;신규연;유규홍
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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    • pp.321-326
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    • 1997
  • Recently, High Range Water Reducing Admixture be used increasingly in other to improve the demanded properties (fluidity, strength, durability etc.) and workability in concrete. These kinds of agent govern quality characteristics (air content, setting time, slump, bleeding etc) by the difference of its dispersing mechanism and performance in manufacture of flowed concrete. Accordingly, in this study, for the purpose of high quality construction in site, the comparative experiment of dispersing ability due to commercially available three types of agent were carried out in paste, mortar and concrete using tow types of cement (I, V). In conclusion, the bleeding reduction by the dispersing ability of agents was verified in the fresh properties of flowed concrete with sea water resistance.

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콘크리트용 블리딩저감제의 개발 및 실용성 검토 (Development and Analysing the Practical Use of Bleeding Reduction Agent for Concrete)

  • 한천구;황인성;신동인
    • 콘크리트학회논문집
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    • 제15권2호
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    • pp.217-224
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    • 2003
  • 블리딩은 재료분리의 일종으로 콘크리트 구조물의 품질을 향상시키기 위해서는 손쉬운 블리딩 저감방안이 요구되고 있다. 그러나, 지금까지 알려진 블리딩 저감대책으로는 재료의 고품질화 및 배합비를 조정하는 등의 방법 외에는 손쉬운 해결책이 없는 실정이었다. 그러므로, 본 연구에서는 콘크리트의 블리딩을 효과적으로 저감할 수 있는 증점제 Type 블리딩저감제의 개발과 그 실용성을 검토한 것으로, 실험결과는 다음과 같다. 즉, 블리딩저감제의 개발은 MC 증점제 : 소포제 : 유동화제를 1 : 0.004 : 0.2의 비율로 혼합하면 가능한 것으로 밝혀졌고. 또한, 개발된 블리딩저감제는 혼입률 증가에 따라 굳지 않은 콘크리트의 유동성, 공기량 및 경화 콘크리트의 압축강도, 내동해성 등 제반 품질은 변동 없고, 블리딩의 저감효과는 우수한 것으로 나타나, 실무에서 콘크리트용 블리딩저감제로 유효하게 활용할 수 있음이 밝혀졌다.

출혈성 쇼크가 심폐기능 및 산.염기평형에 미치는 영향 (Effects of Hypovolemic Hypotension on Cardiopulmonary Functions and Acid-Base Balance)

  • 소원영;이성행
    • Journal of Chest Surgery
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    • 제6권2호
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    • pp.131-142
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    • 1973
  • Studies of cardiopulmonary function and acid-base balance were performed on 29 dogs during control period, during oligemic hypotension and following return of blood to the animals. Intravenous morphine and local anesthesia were used. Fifteen of the 29 animals survived the complete experiment. The 14 animals that failed to survive the experimental period died between 15 to 90 minutes after the onset of bleeding. The results were as follows. 1. The heart rate increased after the onset of bleeding and failed to return to control level following reinfusion. Stroke volume decreased markedly after bleeding and failed to recover after return of blood from the reservoir. Cardiac output also decreased during oligemic hypotension and was maintained at this level after re-infusion. Total peripheral resistance decreased significantly immediately after bleeding, however it increased soon over the pre-bleeding level. Central venous pressure decreased after the onset of bleeding and remained at lower level for the rest of the experimental period. Arterial blood pressure, clown to 40-45 mmHg by acute hemorrhage, was elevated near to control level. Left ventricular work decreased tremendously during oligemic hypotension and failed to return to control level with the re-infusion of blood. Hematocrit value showed no significant decrease after bleeding and increased after re-infusion. Hemoglobin decreased after the onset of bleeding and recovered to control value after re-infusion. 2. The respiratory rate fell rapidly after bleeding from 124 to 29 and remained at this lower level for the remainder of the experiment. The tidal volume increased after bleeding and was maintained at this level for the remainder of the experiment. The respiratory minute volume showed no significant changes throughout the experimental period. Oxygen consumption fell lightly in all animals during oligemic hypotension and returned to normal levels following re-infusion. Arterial oxygen content and arterial oxygen saturation decreased following bleeding and the values returned to normal levels after the return of blood from the reservoir The arterio-venous oxygen difference increased after the onset of bleeding. It failed to return to normal values following re-infusion. Arterial $Pco_2$ decreased in all animals after the beginning of the bleeding. Partial pressure of $Co_2$ continued to fall until re-infusion, after which the values returned toward normal. Animals became acidotic. The pH fell to lower level following bleeding. Lactic acid and lactate: pyruvate ratio also increased during same period. Arterial pH and lactic acid failed to return to control value and lactate: pyruvate ratio increased more after re-infusion. Sodium bicarbonate decreased after bleeding and returned to control value following re-infusion.

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물시멘트비에 따른 바텀애시를 사용한 콘크리트의 특성에 관한 실험적 연구 (An Experimental Study on the Properties of Concrete using Bottom Ash according to Water-Cement Ratio)

  • 이종호;김재환;김용로;강석표;최세진;김무한
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2002년도 학술논문발표회
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    • pp.57-60
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    • 2002
  • Recently, the coal ash production has been increased by increase of consumption of electric power. So it is important to find a reclaimed place and treatment utility for treating coal ash. Accordingly, in this study we performed an experimental study to compare and analyze the Properties of concrete according to W/C and bottom ash replacement ratio. As a result of this study, it was found that the bleeding content was decreased according to decrease of W/C and increase of bottom ash replacement ratio, and the compressive strength of concrete using bottom ash was similar to plain concrete(replacement ratio 0%).

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당류계 안정화제 종류 및 혼입률 변화에 따른 회수수사용 콘크리트의 품질특성 (Qualities of Concrete Using Recycling Water with the Kinds and Contents of Saccaric Based Stabilizing Agent)

  • 김호림;김경민;우종완;한민철;한천구
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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    • pp.660-663
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    • 2004
  • This paper investigate the qualities variety of concrete using recycling water under various kinds and contents of saccaric based stabilizing agent(SSA). Fluidity had little changes with the kinds and contents of SSA. Air contents of concrete with recycled water only shows the tendency. With an increase in SSA contents, air content recovered. For bleeding properties, bleeding shows to be decreased with an increase in SSA contents. The use of recycled water accelerated the setting time. However, with an increase in SSA, setting time showed the similar level of plain concrete. SSA (Btype) had better performance in enhancing compressive strength owing to loss of air content. Although the use of recycled water increased the drying shrinkage compared with that of plain concrete, it tended to decrease with an increase in SSA.

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고로슬래그 골재를 사용한 콘크리트 특성에 대한 실험적 연구 (The Experimental study on the property of concrete which used Blast furnace slag aggregate)

  • 박정우;김상미;김광기;임남기;정상진
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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    • pp.489-494
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    • 2001
  • Several studies have reported that Granulated Blast-Furnace Slag improved the properties of concrete. The Granulated Blast-Furnace Slag could be a good alternative in the shortage of aggregate situation. Slag shows the possibility of influential aggregate and effect of environment preservation. This study presents that the basic properties of fresh concrete using Air-cooled Blast-furnace slag aggregate and Water-cooled Blast-furnace slag aggregate. Testing Factors of this study are concrete slump, slump loss, bleeding, and air contents. The result of this study is below. 1) In case of proportion slag and grave is 50 to 50, the biggest slump value is measured. 2) In the concrete using of air-cooled Blast-furnace slag aggregate, the bleeding capacity is a little. In the concrete using of Water-cooled Blast-furnace slag aggregate, the bleeding capacity goes up to 50% increase. 3) As substitution rate of the granulated blast-furnace slag goes up, air content is increased.

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The Effects of Superplasticizers on the Engineering Properties of Plain Concrete

  • Park, Seung-Bum
    • KCI Concrete Journal
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    • 제11권3호
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    • pp.29-43
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    • 1999
  • The effects of superplasticizers on fresh and hardened concrete were investigated. The experimental program included tests on the workability and slump loss, bleeding, setting time, air content, compressive, tensile and flexural strength, permeability, shrinkage, freeze-thaw durability and creep deformation. Properties of superplasticized concrete were compared with those of conventional and base concretes. Superplasticizers were observed to have an appreciable fluidifying action in fresh concrete. They permitted a significant water reduction while maintaining the same workability. Bleeding of superplasticized concrete was much lower than that of conventional concrete of the same consistency. This indicates that the use of superplasticizers did not affect the tendency of segregation of fresh concrete. The compressive, tensile, and flexural strengths of superplasticized concrete were significantly higher than those of conventional concrete. The permeability and drying shrinkage and creep of superplasticized concrete were less than those of conventional concrete, but there were no significant differences between base and superplasticized concrete. Compared with base concrete, non-air-entrained superplasticized concrete had slightly higher freeze-thaw durability. and superplasticized concrete with an appropriate amount of entrained air Eave even better resistance to freezing and thawing.

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Sustainable controlled low-strength material: Plastic properties and strength optimization

  • Mohd Azrizal, Fauzi;Mohd Fadzil, Arshad;Noorsuhada Md, Nor;Ezliana, Ghazali
    • Computers and Concrete
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    • 제30권6호
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    • pp.393-407
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    • 2022
  • Due to the enormous cement content, pozzolanic materials, and the use of different aggregates, sustainable controlled low-strength material (CLSM) has a higher material cost than conventional concrete and sustainable construction issues. However, by selecting appropriate materials and formulations, as well as cement and aggregate content, whitethorn costs can be reduced while having a positive environmental impact. This research explores the desire to optimize plastic properties and 28-day unconfined compressive strength (UCS) of CLSM containing powder content from unprocessed-fly ash (u-FA) and recycled fine aggregate (RFA). The mixtures' input parameters consist of water-to-cementitious material ratio (W/CM), fly ash-to-cementitious materials (FA/CM), and paste volume percentage (PV%), while flowability, bleeding, segregation index, and 28-day UCS were the desired responses. The central composite design (CCD) notion was used to produce twenty CLSM mixes and was experimentally validated using MATLAB by an Artificial Neural Network (ANN). Variance analysis (ANOVA) was used for the determination of statistical models. Results revealed that the plastic properties of CLSM improve with the FA/CM rise when the strength declines for 28 days-with an increase in FA/CM, the diameter of the flowability and bleeding decreased. Meanwhile, the u-FA's rise strengthens the CLSM's segregation resistance and raises its strength over 28 days. Using calcareous powder as a substitute for cement has a detrimental effect on bleeding, and 28-day UCS increases segregation resistance. The response surface method (RSM) can establish high correlations between responses and the constituent materials of sustainable CLSM, and the optimal values of variables can be measured to achieve the desired response properties.