• Journal of the Korea Institute of Building Construction
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• v.23 no.1
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• pp.35-43
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• 2023

In this study, the mechanical properties of concrete mixed with non-sintered hwangto(NHT) as an alternate material for cement were evaluated, and the compressive strength prediction equation of concrete based on ultrasonic pulse velocity analysis was proposed. Cement replacement rates for mixed NHT were set to 0, 15, and 30%, and design compressive strength was set to 30 and 45MPa to evaluate the effect on the amount of cement and NHT powder. The mechanical properties items analyzed were compressive strength, ultrasonic pulse velocity, and elastic modulus, and were measured on days 1, 3, 7, and 28. As the replacement rate of NHT increased, the mechanical properties tended to decrease. In addition, as a result of analyzing the correlation between compressive strength and ultrasonic pulse velocity, the correlation coefficient(R²) showed a high relationship(R²=0.95) on concrete mixed with NHT.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.359-366
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• 2022

In this paper, the effect of compression levels on the strengths of porous concrete using bottom ash aggregates was analyzed. Coal bottom ash (CBA) was used as aggregate in porous concrete in this study. The aggregate size types used in the CBA concrete mixtures were catagorized into two different ones. One included only a single aggregate particle size and the other included hybrid aggregate particles mixed at a ratio of 8:2 volume proportion. The water-binder ratio was fixed at 0.30, and the compression levels were applied at 0.5, 1.5, and 3.0 MPa valu es to fabricate a porou s concrete specimen. The total porosity, compressive, splitting tensile, and flexural tensile strengths were tested and analyzed. When the compression level increased, the total porosity decreased, meanwhile the compressive, split tensile, and flexural tensile strengths increased. The total porosity of concrete using hybrid aggregate was lower and the strength was larger than those of concrete using single-type aggregate. Finally, the correlation between the total porosity, compressive, split tensile, and flexural tensile strengths of porous concrete were presented. The total porosity and strength characteristics showed an inversely proportional correlation.

• Magazine of the Korea Concrete Institute
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• v.14 no.6
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• pp.88-95
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• 2002

최근 국내에 60층을 초과하는 초고층 구조물들이 많이 건설되고 있으며, 콘크리트 품질의 향상 특히 콘크리트의 고강도화에 힘입어 이를 이용한 철근 콘크리트 고층 구조물들이 증가하고 있다. 이에 따라 이들 초고층, 초대형 구조물을 지지할 수 있는 고축력, 고연성의 기둥에 대한 설계 및 시공이 요구되고 있으며, 이에 가장 적합한 구조요소라 할 수 있는 콘크리트 충전 강관기둥(Concrete Filled Steel Tube Columns : CFT Columns)의 설계 및 시공에 관심이 높아지고 있다. 이러한 콘크리트 충전 강관기둥은 콘크리트가 강관에 의해 둘러싸여지기 때문에 축하중 저항 능력이 증가되는 장점과 동일한 단면으로 H형강을 사용한 순수 철골조 H형강 기둥의 강축(strong axis)과 약축(weak axis) 문제해결과 동시에 강성 (stiffness)을 증가시킬 수 있으며, 내화 성능이 향상되고 거푸집 대체 재료로 사용되는 등 여러 가지 장점을 지니고 있다. 한편 충전 강관기둥에 작용하는 축하중은 대부분 콘크리트가 부담하게 되는데 이러한 충전강관 기둥의 장점을 극대화하기 위해서는 보통강도 콘크리트보다는 압축강도 및 탄성계수가 큰 고강도 콘크리트의 사용은 불가피하게 된다.(중략)

• Korean Journal of Agricultural Science
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• v.23 no.1
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• pp.61-69
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• 1996

This study was performed to evaluate the engineering properties of permeable polymer concrete with fillers and unsaturated polyester resin. The following conclusions were drawn. 1. The highest strength was achieved by stone dust filled permeable polymer concrete, it was increased 17% by compressive, 148% by tensile and 188% by bending strength than that of the normal cement concrete, respectively. 2. The static modulus of elasticity was in the range of $1.17{\times}10^5{\sim}1.32{\times}10^5kg/cm^2$, which was approximately 53~56% of that of the normal cement concrete. Stone dust filled permeable polymer concrete was showed relatively higher elastic modulus. The poisson's number of permeable polymer concrete was less than that of the normal cement concrete. 3. The dynamic modulus of elasticity was in the range of $1.3{\times}10^5{\sim}1.5{\times}10^5kg/cm^2$, which was approximately less compared to that of the normal cement concrete. Stone dust filled permeable polymer concrete was showed higher dynamic modulus. The dynamic modulus of elasticity were increased approximately 10~13% than that of the static modulus. 4. The water permeability was in the range of $3.076{\sim}4.390{\ell}/cm^2/h$, and it was largely dependent upon the mix design. These concrete can be used to the structures which need water permeability. 5. The compressive strength, tensile strength, bending strength and elastic modulus were largely showed with the decrease of water permeability.

• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.269-278
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• 2008

The primary object of the paper is to understand the compressive buckling characteristics of steel-concrete structures through the finite element analysis. The buckling pattern, compressive strength and stiffness of the steel plate concrete structures were investigated by the FEM analysis using the variations of B/t ratios and stud pitches. The investigation was focused on steel plate concrete structures with and without ribs placed on the surface of steel plates. The results of the FEM analysis were compared with the previous results from the theoretical equations. Conclusively, the buckling of the steel plate concrete structures occurred in the transverse direction of the loading direction. The stiffness of the steel plate concrete structure with ribs is greater than the one without the stiffened rib. The compressive strength in the FEM analysis is similar to that of JEAG 4681 and it showed 20% greater value than that of the proposed equations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.111-118
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• 2019

This study examined the effect of amorphous metallic (AM) fibers on the spalling properties of ultra high strength concrete. Six specimens with concrete strengths of 100 MPa and 150 MPa were evaluated with mix proportions of polypropylene (PP) fibers of 0.15% by concrete volume, and proportions of AM fibers of 0.3% and 0.5% by concrete volume. These specimens were then heated in accordance with the ISO-834 heating curve. The movement of water vapor through a pore network formed by molten PP fibers was found to be a dominant factor controlling the spalling of high-strength concrete. Spalling control was not found to be significantly affected by the addition of 0.3% AM fibers; however, when 0.5% AM fibers was added, cracking was limited and so were paths for water vapor migration, increasing the likelihood of a moisture clog and creating the differential internal pressure often blamed for concrete spalling.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.949-952
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• 2008

화재안전 신뢰성이 확보된 고강도 콘크리트 구조물의 시장 공급을 위하여 GS건설에서는 2005년 부터 고강도 콘크리트 구조물의 강도 영역별 폭렬 저감 및 거동 안전성 평가와 수치해석 방법을 통한 경제적인 설계방법를 최종 연구목표로 하여 현재까지 콘크리트 재료의 열적 특성 확보와 구조부재 화재 특성 연구를 수행해 왔다. 강도발현, 시공성, 내화성능과 경제성에 대한 분석을 해외연구 기관에 의뢰하여 섬유혼입공법을 선정한 후 이에 대한 재료의 물리적 특성과 역학적 특성 실험결과를 바탕으로 고강도 콘크리트 구조부재의 내화성능을 예측 분석할 수 있도록 비열 모델, 열전도율모델, 압축강도 모델, 탄성계수 모델을 구축하였다. 또한 기둥과 보에 대한 내화실험을 실시하여 내화성능을 평가하였으며, 이에 대한 열적 해석을 병행하여 진행하였다.

• Magazine of the Korea Concrete Institute
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• v.14 no.2
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• pp.37-44
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• 2002

콘크리트의 내화성능에 대한 다각적인 연구가 1970년대부터 원자로의 안정성 확보차원에서 진행되어 왔으며 특히 콘크리트의 취성파괴(brittle failure)등에 대한 연구가 많다. 콘크리트의 내화성이란 화재로부터 보호되고 고열환경에 견디는 재료적 특성 즉 화재온도 1,00$0^{\circ}C$ 정도의 고온을 30분에서 3시간 정도를 받은 경우 콘크리트 중에 매립된 철근 등 철강을 소정의 온도 이하고 유지하기 위한 피복 역할을 유지하면서 구조물의 큰 변형이나 붕괴 등을 막기 위한 소요 압축강도 및 영계수 등의 성능을 가지고 있는 성질을 말한다.(중략)

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.202-208
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• 2014

For evaluating basic structural behavior of HVFA (High Volume Fly Ash) concrete, several tests are performed considering different ratios of fly ash replacement and structural evaluation regarding compressive strength, elasticity modulus, stress-strain relationship, and bond strength is also performed. Test results show that elasticity modulus of HVFA concrete has close relationships with compressive strength and fly ash replacement ratio. The ultimate strain shows slight difference from domestic design code. On the other hand, there are no differences between general concrete and HVFA concrete for elasticity modulus and bond strength.

• Clean Technology
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• v.7 no.2
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• pp.109-117
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• 2001

Whereas commonly used to make concrete having rich water contents as binder or mineral admixture, blast furnace slag has been rarely applied to manufacture in concrete based products having poor water contents. This study, for the multi-recycling of blast furnace slag, is to analyze strength enhancement mechanism of concrete based products using blast furnace slag. The results of this study are following. We found that blast furnace slag is very effective mineral admixture to manufacture high strength spacer having over $400kgf/cm^2$ in compressive strength. Also, enhancement of strength by blast-furnace slag are responsible to densified grading and pozzolanic reaction.