• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.957-960
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• 2008

In this study, it was investigated fire resistance properties of high strength concrete column using Engineered Cementitious Composites(ECC) permanent form as a countermeasure for explosive spalling of concrete on fire. As a test result, it was appeared that ECC permanent form is available as fire resistance method of high strength concrete if it is developed manufacturing technique and scheme for application controlling heat penetration through interface of permanent form and high strength concrete, and setting up mix proportion and thickness of ECC.

• Fire Protection Technology
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• s.43
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• pp.34-45
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• 2007

고강도 콘크리트 기둥의 내화성능을 향상시키기 위한 설계지침을 개발하기 위한 연구프로그램의 전체적 결과가 도출되었다. 고강도 콘크리트 기둥과 보통강도 콘크리트 기둥의 내화성능을 비교하였다. 화재상태에서 고강도 콘크리트 기둥의 구조적 거동에 영향을 미친는 다양한 요소에 대하여 토론하였다. 설계 가이드라인은 고강도 콘크리트 기둥의 폭렬을 줄이고 내화성능을 향상시키기 위하여 준비하였다.

• Magazine of the Korea Concrete Institute
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• v.3 no.4
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• pp.125-132
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• 1991

$\beta$-NSF 계통의 콘크리트용 고성능감수계를 독자적으로 제조하여(제품C)국내에서 유통되고 있는 $\beta$-NSF계 고성능감수제들과 콘크리트의 유동화특성 및 고강도콘크리트의 특성을 비교검토한 결과는 다음과 같다. 가. $\beta$-NSF계 고성능감수제중에서 M제품과 C제품의 유동화성능 및 고강도성능이 다른 감수제에 비하여 전반적으로 좋게 나타났다. 나. $\beta$-NSF계 고성능감수제를 첨가한 모든 콘크리트는 감수제를 사용하지 않은 일반 콘크리트에 비하여 흐름도의 경시변화가 크며, 동결융해에 대한 저항성이 현저히 떨어지는 것으로 나타났다.

• Journal of the Korea Concrete Institute
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• v.19 no.3
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• pp.377-383
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• 2007

In recent years the field application of high performance concrete has been increased to improve the quality and reliability of concrete structures. The mix design of the high performance concrete includes the 2 set-off mixture theory of mortar and coarse aggregate and that of paste and aggregate. The 2 set-off mixture theory of mortar and coarse aggregate has a problem of having to determine its value through repeated experiments in applying the rheological characteristics of mortar. The 2 set-off mixture theory of paste and aggregate has never been applied to high performance concrete since it doesn't take into account the relationship between optimum fine aggregate ratio and unit volume of powder nor does it consider the critical aggregate volume ratio. As the mixture theory of these high performance concretes, unlike that of general concrete, focuses on flowability and charge-ability, it does not consider intensity features in mix design also, the unit quantity of the materials used is determined by trial and error method in the same way as general concrete. This study is designed to reduce the frequency of trial and error by accurately calculating the optimum fine aggregate ratio, which makes it possible to minimize the aperture of aggregate in use by introducing the maximum density theory to the mix design of high performance concrete. Also, it is intended to propose a simple and reasonable mix design for high performance concrete meeting the requirements for both intensity and flowability. The mix design proposed in this study may reduce trial and error and conveniently produce high performance concrete which has self-chargeability by using more than the minimum unit volume of powder and optimum fine aggregate with minimum porosity.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2009.04a
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• pp.61-66
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• 2009

최근 초고층 건축물 등에 적용되는 고강도콘크리트의 내화성능에 대한 문제점이 제기됨에 따라 국토해양부에서는 고강도콘크리트 내화성능 관리 기준을 고시한 바 있으며, 건설업계에서도 이에 대응하기 위해 다양한 기술 검토가 이루어지고 있다. 본 연구에서는 고강도콘크리트의 취약점으로 제기되고 있는 화재시의 폭렬문제에 대한 대응방안으로서 기존 연구를 통해 내화성능이 우수한 것으로 보고되고 있는 ECC 를 영구거푸집으로 활용한 고강도콘크리트의 내화성능을 검토하였다. ECC 영구거푸집을 활용한 고강도콘크리트 기둥부재의 내화성능 검토 결과, 영구거푸집과 고강도콘크리트 계면으로의 열 침투를 제어할 수 있도록 부재 생산 및 구축 방안을 검토하고, ECC의 적정 배합 및 두께를 확보한다면 고강도콘크리트의 내화성능 확보기술로서의 활용이 가능할 것으로 판단된다. 또한, 내화성 영구거푸집으로서의 단순 활용 방안 이외에 ECC의 우수한 물리적 성능을 활용하여 구조성능을 분담할 수 있는 방안으로의 지속적 검토가 필요할 것으로 판단된다.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.479-480
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• 2010

The efforts to achieve high-performance, durable reinforced concrete structures have increased the demands for improving the performance of both the concrete and the reinforcing materials. Researches for the hybrid reinforcing technique, which is maximizing the performance of high-strength concrete structures by applying the combination of high performance reinforcing materials, were performed in this study.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.2
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• pp.135-142
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• 2009

This study investigates the characteristic properties of strength, flowability, durability and drying shrinkage to control strength and to reduce heat of hydration of high performance concrete using crushed stone fines. According to the experimental results, when crushed stone fines are increased every 10%, $10{\sim}15%$ of compressive strength is decreased and flowability of high performance concrete is effectively improved due to the decrease of modulus of deformation and confined water ratio. When crushed stone fines are replaced every 10%, $4^{\circ}C$ of the highest adiabatic temperature rise is decreased by reducing the unit cement. However, 5% of drying shrinkage is increased in the same condition In the meantime, durability of high performance concrete is excellent, having over 100% of good relative dynamic modulus of elasticity due to fineness of formation mused by the increase of the unit powder content and the improvement of flowability, without regard to the replacement of crushed stone fines. Therefore, It can be said that the usage of crushed stone fines can control the strength of high performance concrete by replacement and reduce heat of hydration.

• KSCE Journal of Civil and Environmental Engineering Research
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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.

• Magazine of the Korean Society of Agricultural Engineers
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• v.28 no.2
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• pp.74-86
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• 1986

유동화콘크리트의 공학적 특성에서 시간-의존거동을 확인하기 위하여,나프타렌 설폰산염 폴리머 고축합물인 Rheobuild 1000과 메라민 설폰산염 고축합물인 NP-20의 고성능감수제를 사용한 유동화콘크리트와 보통콘크리트를 제조하여 비교.고찰을 행하였으며, 고성능감수제의 종류 및 함량이 콘크리트의 공학적 특성에 미치는 영향을 구명하기 위하여 재령 3일, 14일, 28일, 60일, 90일, 180일의 압축강도를 측정, 조기 및 장기압축강도를 조사하였고, 인장강도 및 탄성 변형에 미치는 영향을 조사하였다. 또한 습윤 및 에어콘디션의 양생조건하에서 시간의 경과에 따른 건조수축 및 크리이프 변형을 조사.분석함으로써 유동화콘크리트의 시간-의존거동을 확인하였다. 실험결과, 사용 고성능 감수제의 종류에 따라 차이는 있으나, 고성능 감수제의 사용은 일반적으로 워커빌리티 성능을 개선하고 압축 및 인장도를 크게 향상시키며, 탄성계수는 보통의 콘크리트에 비하여 높게 나타났다. 또한 건조수축 및 크리프 변형의 감소에 매우 양호한 결과를 나타내어 앞으로 건설용 용도로써 효과적인 것으로 판단되었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6A
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• pp.561-572
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• 2010

This paper is a study about application of recently proposed Performance Based Mixture Design (PBMD) for design of high strength concrete (HSC) to obtain HSC mix proportion that satisfies required performances. The PBMD method which uses Satisfaction curve based on a Bayesian method is a performance oriented concrete mix proportion design procedure easily applicable to any condition and environment for a possible replacement to the current prescriptive design standards. Based on extensive experimental results obtained for various materials and performance parameters of HSC, the application feasibility of the developed PBMD procedure for HSC has been verified. Also, the proposed PBMD procedure has been used to perform application examples to obtain desired target performances of HSC with optimum concrete mixture proportions using locally available materials, local environmental conditions, and available concrete production technologies. The validity and precision of HSC mix proportion design obtained using the PBMD method is verified with the experimental and ACI presented results to check the feasibility for actual design usage.