• Title, Summary, Keyword: slump loss

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Slump Loss of High Strength Concrete Containing Mineral Admixture and Gypsum (광물질 혼화재 및 석고를 사용한 고강도 콘크리트의 슬럼프 손실)

  • 김기형;최재진
    • Journal of the Korean Society of Safety
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    • v.12 no.1
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    • pp.101-107
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    • 1997
  • High strength concrete(HSC) using high range water reducing admixture (HRWR) has the defect which severe slump loss occurs according to elapsed time. For using HSC without any trouble, special caution and countermeasure against this problem are necessary. In this study, for minimizing the slump loss of HSC, mineral admixture( flyash, ground granulated blast furnace slag ) and gypsum were used experimentally. Flyash and ground granulated blast furnace slag are effective in reducing the slump loss of HSC. Especially, the slump loss of HSC containing mineral admixture and gypsum Is minimized by the aggregation inhibiting action of gypsum. Cement substituted with flyash 30% or ground granulated blast furnace slag 50% by weight are very effective in minimizing the slump loss.

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A Study for Reducing the Slump Loss of Concrete Using High Range Water Reducing Admixture (고성능감수제(高性能減水劑)를 사용한 콘크리트의 유동성(流動性) 손실(損失)을 저감(低減)시키기 위한 연구(硏究))

  • Moon, Han Young;Kim, Ki Hyung
    • Journal of The Korean Society of Civil Engineers
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    • v.12 no.3
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    • pp.81-90
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    • 1992
  • This study gives results of 1aboratory investigations to minimize the slump loss of concrete using high range water reducing admixture (HRWR). Various factors influencing on the slump loss such as cement type, HRWR type and dosage time are investigated. The acquired results indicated that 30 minutes delayed dosage of HRWR is very effective on reducing the slump loss though this tendency makes a difference to some extent according to cement and HRWR type. For the most part, the more usage of HRWR increases, the higher the slump loss occurs and concrete using ordinary portland cement has the highest slump loss and concrete using fly ash 20% replacement cement with HRWR of naphthalene type has the good effect on reducing the slump loss.

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Estimation and Analysis of Slump Loss in Ready Mixed Concrete (레드믹스트 콘크리트의 슬럼프손실량(損失量)의 추정(推定) 및 슬펌프손실(損失)에 영향을 미치는 요인분석(要因分析))

  • Moon, Han Young;Choi, Jae Jin
    • Journal of The Korean Society of Civil Engineers
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    • v.6 no.2
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    • pp.23-34
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    • 1986
  • Multiple regression equation was derived for estimation of slump loss in ready mixed concrete and usefulness of the equation was verfied by field test. Factors affecting slump loss were examined and analyzed for transport distance and transport time of ready mixed concrete. The analysis showed that wait and discharge time of ready mixed concrete in job site caused difficulty in the slump control. To determine the influence of the other factors such as mix proportion, temperature of concrete, and dosage of admixture, experimental tests were performed. Generally, there was no significant difference in slump loss according to cement content and initial slump level. For one retarder, more slump loss was found, but difference according to dosage of admixture was not recognized.

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An Experimental Study on the Factors Influencing on the Slump Loss of High Strength Concrete (고강도콘크리트의 유동성 손실에 영향을 미치는 요인에 대한 실험적 연구)

  • 문한영;김기형;문대중
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.94-99
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    • 1992
  • In this study , some factors such as mix proportion, type and dosage of high range water reducing admixture(HRWR) and natural pozzolanas influencing on the slump loss of high strength concrete(H.S.C) using HRWR were investigated for reducing the slump loss. The acquired results indicated that the slump loss of H.S.C was affected according to cement content, sand percentage and type and dosage of HRWR and fly ash was superior to ground granulated blast furance slag in reducing the slump loss of H.S.C.

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An Experimental Study on the High Strength Concrete Properties for Mixing Methods and Elapsed time (고강도 콘크리트의 배합방법과 운반특성에 관한 실험적 연구)

  • 권녕호;안재현;박칠림
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.7-12
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    • 1992
  • The aim of this study is to develop economical High-Strength and High-Quality Concrete, and to assure quality control of Concrete in the field. For this purpose, Five types of Mixing Methods are examined and the relationship between slump loss and slump recovery by transport is studied. As a result, workability and strength are dependent on the Mixing Method, although the Mixing proportions are same, Also, adding admixture in the field is proposed as an alternative to consider the relationship between slump loss and slump recovery.

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A Study on the Fundamental Properties of High Strength Concrete Using Silica Fume (실리카흄 사용 고강도콘크리트의 기초적 성질에 대한 연구)

  • 문한영;김기형;문대중
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.11-17
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    • 1993
  • In this study, the fundamental properties of High-Strength Concrete(HSC), such as the slump loss, the temperature increment, the strength development, are considered by experiment. In reducing the temperature and the slump loss, and developing the strength of HSC, the application of silica fume as an admixtures is very effective. And when gypsum is added, the slump loss is reduced and the strength of HSC is improved remarkably, but the temperature of concrete is increased, thus a more study to reduce the temperature increment is required

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Improvement of Properties of High Strength Concrete Using Fly Ash and Gypsum (플라이 애시 및 석고를 활용한 고강도 콘크리트의 성능개선)

  • 김기형;최재진;최연왕
    • Journal of the Korea Concrete Institute
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    • v.11 no.5
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    • pp.99-105
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    • 1999
  • In producing high strength concrete, the most practical method is to use high range water reducing admixture(HRWR). Workabili쇼 of concrete using HRWR varies rapidly with elapsed time after mixing. Effects of fly ash and gypsum on slump loss and compressive strength of concrete were examined by experiment in this study. The slump loss of high strength concrete was reduced with increase of substitution ratio of fly ash. When 2~4% gypsum of cement weight was applied, the reduction of slump loss was not prominent and strength increase appeared at all test ages.

Properties of Concrete Using Slump Retentive Superplasticizer (고성능 AE감수제를 사용한 콘크리트의 기초적 성질)

  • 최재진;김은겸;신치범
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.638-644
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    • 1999
  • Workability time of superplasticized concrete is maintained generally for 30-60 minutes only. Therefore it is of great advantage for the concrete producer to use a high range water reducer which provides an extended slump life. Recently slump retentive srperplasticizer has been developed. Concrete mixing tests were done to know slump, setting, air content, bleeding and hardening characteristics of concrete using slump retentive superplasticizer. With slump retentive superplasticizer, high quality concrete was produced and slump loss of concrete was reduced in big way, making long transportation time possible as a practical alternative to on-site addition.

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Application of Powdered Superplasticizer to Improve of Slump Loss Rate in Recycled Aggregate Concrete (재생 골재 콘크리트의 슬럼프 손실 개선을 위한 분말형 감수제의 활용)

  • Yang, Keun-Hyeok;Sim, Jae-Il;Lee, Jae-Sam;Chung, Heon-Soo
    • Journal of the Korea Concrete Institute
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    • v.18 no.5
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    • pp.649-656
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    • 2006
  • In this study, powered superplasticizer(PSP) agents to improve the slump loss rate of recycled aggregate concrete were developed. To evaluate the variation of fluidity against elapsed time and the mechanical properties, twenty four specimens whose main variables had the mixing condition of aggregates, such as natural and recycled gravels, and natural and recycled fine aggregates, were tested. The concrete slump with a liquid superplasticizer greatly decreased against the elapsed time and dropped by less than 50% of initial slump after two hours. However the concrete slump with the PSP agents hardly varied until after half an hour and maintained more than 85% of initial slump even after an hour. Also the PSP agents made the compressive, splitting tensile, and flexural strength of concrete increased and the shrinkage strain decreased. Considering the properties improvement of concrete, it can be recommended that optimum mixing amount of the PSP agents should be 5% of the amount of cement.

Rheology Properties of Belite-rich Cement Mortar Added Blastfurnace Slag and Polycarbonate-based Superplasticizer (고로슬래그와 폴리카르본산계 유기 혼화제를 첨가한 Belite-rich Cement 모르타르 유동특성)

  • 송종택;송종택;조현태;황인수;박춘근
    • Journal of the Korean Ceramic Society
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    • v.37 no.2
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    • pp.145-151
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    • 2000
  • In order to investigate the rheological properties of belite-rich cement(BRC) added polycarbonate-based superplasticizer and blastfurnace slags which have different blaines at 4500, 6000 and 8000$\textrm{cm}^2$/g, the change of minislumps and mortar slumps are measured with time. The rheological properties improve as specific surface area of added slag decreases or amount of polycarbonate-based superplasticizer increases. The slump loss can be controlled effectively by the steric hinderance effect of polycarbonate-based superplasticizer. According to the results, when mix proportion of the mortar is 1.5% mass content of superplasticizer and 30% mass addition of blastfurnace slag which blaine is 4500$\textrm{cm}^2$/g, the best mortar slump can be achieved without any significant segregation of materials.

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