• 콘크리트학회지
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• 제9권3호
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• pp.149-156
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• 1997

시멘트 모르타르의 압축강도 향상을 휘하여 분말혼화제를 제조하였으며,분말혼화재 사용에 따르는 유동성 감소를 억제하고자 고유동화제를 사용하였다. 분말혼화재(FAS)는 불산부생 II형 무수석고와 플라이애쉬 및 실리카흄을 혼합제조하여 시멘트 대신 각각10,20 wt% 씩 치환하였다. 물/고형분비(W/S)=0.40에서 FAS 로 치환된 시멘트 페이스트의 유동성은 저하되었고, 유동성 저하의 억제를 위한 고유동화제는 NSF와 NT-2가 효과적이었다. 시멘트 모르타르의 유동성은 II형 무수석고의 분말도가 미세할수록 증가하였고, 유동성저하는 FAS를 10 wt% 치환하였을 때 작게 나타났다. 압축강도는 10 wt%치환한 공시체가 20 wt%치환한 것보다 높게 나타났고 특히 $\gamma$ 를 10 wt%치환한 공시체( CI )에서 가장 높은 압축강도값을 나타내었다.

• 한국건설순환자원학회논문집
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• 제9권3호
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• pp.276-286
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• 2021

기존 고유동 콘크리트는 소요의 유동성과 작업성 확보를 위해 대부분 단위시멘트량이 높은 고강도 콘크리트 영역으로써, 현재 사용되고 있는 대부분의 콘크리트 구조물이 보통강도(18~35MPa) 수준임을 감안한다면 현실적인 사용범위확대 및 실용성에 한계가 있었다. 고유동 콘크리트의 사용범위를 확대하기 위해 보통강도 수준에서도 유동성과 점성을 발휘할 수 있고 일반건축물뿐만 아니라 특수건축물에서도 사용가능하며, 타설시간과 인건비를 대폭 감축할 수 있는 보통강도 고유동 콘크리트의 개발이 필요한 실정이다. 보통강도 고유동 콘크리트의 개발은 유동성 및 점성을 발휘하여 자기 충전성을 확보함으로써 다짐작업 최소화에 따른 인건비 감축, 공사비 절감, 공기 단축 등의 시공효율성 뿐만 아니라 공사품질을 향상시킬 수 있다. 본 연구에서는 출발원료(WR, HB, RT)의 조합별로 PCE를 제조하고 링플로콘과 회전형 점도계를 사용하여 시멘트 페이스트의 레올로지 특성을 분석하였다. 실험결과 WR 80%, HB 6.5% RT 13.5%를 조합한 PCE를 적용할 경우, 결합재량이 낮은 보통강도 고유동 콘크리트에서 소성점도를 확보하면서 항복응력은 최소화시킬 수 있으며 동시에 높은 분산효과로 인한 고유동성의 확보가능성을 확인할 수 있었다.

• 한국해양공학회지
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• 제12권1호
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• pp.153-161
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• 1998

This paper is to investigate the Fluidity of Antiwashout Underwater Concrete containing Fly Ash. The results of study are concluded as follows: the increase in Slump Flow value did not happen in the plain concrete which was replaced cement by Fly Ash; however, the maximum value could reach in the replacement of 30% of Fly Ash by weight of cement in the Fly Ash replaced concrete. On the condition of Fly Ash-Antiwashout Underwater Concrete in expecting 50 cm of the Slump Flow, it was necessary that the usage amount of Superplasticizer be around 1% of unit Binder, and 1.5% in 60 cm of the Slump Flow, respoectively.

• 한국건축시공학회지
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• 제7권1호
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• pp.57-62
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• 2007

Generally, the strength of concrete depends on factors of materials, mix proportions, compaction, manufacturing methods and curing and so on. And recently, it has increased the using of crushed sand for concrete due to the exhaustion of good natural aggregate. In case of Korea, in 2004, the using ratio of crushed sand occupies about 28% of whole fine aggregate. This is an experimental study to compare and analyze the influence of W/B ratio and replacement ratio of crushed sand on the fluidity and compressive strength of high strength concrete. For this purpose, the mix proportions of concrete according to the W/B (31.5, 27.5, 23.5%) and replacement ratio of crushed sand (0, 20, 40%) was selected. And then air content, slump-flow, a-lot, compressive strength test were performed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.317-322
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• 2001

This paper investigates the influence of fine aggregates on bleeding of concrete. According to test results, as water content decreases, crushed sand content increases, fluidity shows decline tendency. As for aggregates kinds, concrete using sea sand shows most fluidity loss among the tested results. Compressive strength gains highly when crushed sand is used. As for bleeding of concrete, bleeding shows decline tendency because of increasing in powder content and filling effect of voids. Bleeding amount is in a decreasing order of magnitude for concretes made with the following aggregates: sea sand, river sand, and crushed sand. Accordingly, crushed sand mixed with river sand and sea sand with certain proportion enable to reduce bleeding and enhance strength.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.473-476
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• 2006

As a part of efforts to obtain high quality and economical efficiency of concrete, blast-furnace slag has been utilized by means of cement replacement. Therefore superior performance can be ensured, environmental pollution can be prevented and economical advantage can be obtained with utilization by cement replacement. But the studies on the blast-furnace slag are not systematic and reasonable. So, it was planed that basic data in regard to technique of manufacturing and economic improvement of concrete is showed with experimental comparison and investigation of Fluidity and engineering properties of concrete utilizing blast-furnace, industry by-product, as cement replacement in this study.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.473-476
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• 2003

This study discusses the use of anti-shrinkage agent as the method to reduce autogenous and drying shrinkage. According to results, as for the fundamental properties of high performance concrete, fluidity and strength decrease with an increase of the adding ratio of anti-shrinkage agent, but air content increases. Compared with plain concrete, autogenous and drying shrinkage are reduced by 12~52% and 4~22% respectively upto the adding rario of anti-shrinkage agent of 2.0%. When expansive additive is added by 5.0%, they are also reduced by 38~95% and 15~50% respectively. Therefore, as expansive additive of 5.0% and anti-shrinkage agent of 1.0% are added to high performance concrete of around W/B 30%, it is considered that fluidity and strength are hardly influenced, and in addition, crack by shrinkage can be prevented effectively.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.81-87
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• 2003

The purpose of this study is the development of a recycling process to recover the hydrated ability of cement hydrate which accounts for a large proportion of cementitious powder by concrete waste in order to recycle cementitious powder by concrete waste as recycle cement. Therefore, after having theoretical consideration based on the properties of high-heated concrete, we consider the properties of hydration of cementitious powder in hardened mortar under various temperature conditions. As a result of experiment, it is revealed that an effective development of recycling cement is possible since the cementitious powder by concrete waste recovers a hydraulic property during burning at $600^{\circ}C$ or $700^{\circ}C$. And it is shown that the fluidity of mortar decreases rapidly as the burning temperature of recycle cement increases. however, the improved effect of fluidity is predominant if adding the additive such as fly-ash or blast furnace slag.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.437-440
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• 2006

Generally, the strength of concrete depends on factors of materials, mix proportions, compaction, manufacturing methods and curing and so on. And recently, it has increased the using of crushed sand for concrete due to the exhaustion of good natural aggregate. This is an experimental study to compare and analyze the fluidity and compressive strength of ultra-high strength concrete according to the replacement ratio of crushed sand. For this purpose, the mix proportions of concrete according to the W/B ratio and replacement ratio of crushed sand was selected. And then air content, slump-flow, O-lot, compressive strength test were performed.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2001년도 학술논문발표회
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• pp.46-51
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• 2001

As a rule, in case of CFT for high-rise building, high strength concrete is required since it should have high fluidity, segregation resistance and large proportion of cement per unit considering the fi11ing beneath the diaphragm. However, regarding the low-rise building under 20 stories, it is somewhat difficult to use high strength concrete. This is a fundamental study to develop a concrete with normal strength and high fluidity for CFT of low-rise building, whose purposes are in speculating several kinds of changes in concrete's characteristics through various experiments and offering basic documents for practicalization in si to and production through mock-up test.