• 한국구조물진단유지관리공학회 논문집
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• 제8권2호
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• pp.213-220
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• 2004

본 연구의 목적은 전단 보강근이 없는 강섬유 보강 콘크리트 보의 전단내력을 강섬유 계수를 이용하여 평가하기 위한 것이다. 이를 위하여 재료 및 부재 수준의 2단계 연구를 수행하였다. 기존 및 본 연구 결과에 의하면, 강섬유 보강 콘크리트의 주요 요인은 강섬유 계수로 평가되었으며, 이를 근거로 한 강섬유 보강계수가 제안되었다. 또한 기 제안된 전단내력식을 평가한 결과, 신성우 제안식이 강섬유 비보강 보의 내력을 적절히 평가하는 것으로 나타났다. 따라서 신성우 제안식에 강섬유 계수를 곱한 강섬유 보강 콘크리트의 전단내력식이 회귀분석에 의하여 제안되었다.

• Computers and Concrete
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• 제26권3호
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• pp.275-283
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• 2020

Reinforced concrete (RC) does not provide sufficient resistance against impacts and blast loads, and the brittle structure of RC fails to protect against fractures due to the lack of shock absorption. Investigations on improving its resistance against explosion and impact have been actively conducted on high-performance fiber-reinforced cementitious composites (HPFRCCs), such as fiber-reinforced concrete and ultra-high-performance concrete. For these HPFRCCs, however, tensile strength and toughness are still significantly lower compared to compressive strength due to their limited fiber volume fraction. Therefore, in this study, the tensile behavior of slurry-infiltrated fiber-reinforced cementitious composites (SIFRCCs), which can accommodate a large number of steel fibers, was analyzed under static and dynamic loading to improve the shortcomings of RC and to enhance its explosion and impact resistance. The fiber volume fractions of SIFRCCs were set to 4%, 5%, and 6%, and three strain rate levels (maximum strain rate: 250 s^-1) were applied. As a result, the tensile strength exceeded 15 MPa under static load, and the dynamic tensile strength reached a maximum of 40 MPa. In addition, tensile characteristics, such as tensile strength, deformation capacity, and energy absorption capacity, were improved as the fiber volume fraction and strain rate increased.

• 한국세라믹학회지
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• 제52권1호
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• pp.13-18
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• 2015

The fabrication method used for mineral hydrate is similar to that of ALC (autoclaved lightweight concrete), but the fabrication of normal slurry with a considerable amount of a foaming agent is difficult due to material separation and collapse of the slurry. Therefore, the development of fabrication methods for normal slurry is necessary. The final product, mineral hydrate insulation, has excellent thermal properties but poor strength characteristic given the many pores. In this study, in order to fabricate normal slurry, the viscosity and foaming time of the slurry were controlled. The mixing ratio of the starting material and the polypropylene fiber was controlled to improve the strength. Mineral hydrate with polypropylene fiber showed a higher strength than that without this type of fiber. Specifically, the compressive strength of mineral hydrate with 2% polypropylene fiber added to it was more than 40% higher than that without the fiber.

• 콘크리트학회논문집
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• 제18권3호
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• pp.361-370
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• 2006

본 연구에서는 국내외 강섬유보강 콘크리트보의 실험값 및 이론식을 분석하여 강섬유의 보강효과 및 부재의 역학적 거동을 규명하였고, 기존의 휨강도식보다 더 정확하고 합리적인 휨강도식을 제안하였다. 제안된 휨강도식은 실험값과 좋은 일치를 보여주었고, 강섬유보강 콘크리트보의 휨강도식은 강섬유보강효과뿐만 아니라 철근의 변형률 경화효과도 함께 고려하는 것이 적절함을 알 수 있었다.

• 한국농공학회논문집
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• 제46권6호
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• pp.47-58
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• 2004

As concrete structures are getting larger, higher, longer and more specialized, it is more required to develop steel fiber concrete and apply to the real world. In this research, it is aimed to have fatigue strength examined, varying the steel fiber content of 0%, 0.75%, 1.00%, 1.25% by experimental study of fatigue behavior of the steel fiber reinforced concrete continuous beams under cyclic loading. The ultimate load and initial load of flexural cracking were measured by static test. In addition, the load versus strain relation, load versus deflection relation, crack pattern and fracture mode by increasing weight were observed. On the other hand, the crack propagation and the modes of fracture according to cycle number and the relation of cyclic loading to deflection relation and strain relation were investigated by fatigue test. As the result of fatigue test, continuous beam without steel fiber was failed at 60 ~ 70% of The static ultimate strength and it could be concluded that fatigue strength to two million cyclic loading was arround 67.2% by S-N curve. On the other hand, that with steel fiber was failed at 65 ~ 85% of the static ultimate strength and it could be concluded fatigue strength to two million cyclic loading around 71.7%.

• 한국구조물진단유지관리공학회 논문집
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• 제14권1호
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• pp.102-108
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• 2010

본 연구의 목적은 폐 PET병을 재활용하여 만든 섬유(RPET)를 콘크리트 부재에 적용시키기 위한 성능 평가에 있다. RPET 섬유보강 효과를 평가하기 위해서 압축강도, 탄성계수, 쪼갬인장강도와 같은 기초물성실험과 건조수축균열실험을 수행하였다. 기초물성실험에서 RPET의 혼입률이 증가할수록 RPET 보강 콘크리트의 압축강도와 탄성계수는 감소하였고, 쪼갬인장강도는 증가하였다. 건조수축 실험에서 자유건조수축은 증가하였다. 반면에 구속건조수축의 경우 RPET 섬유에 의한 인장 저항성의 증가로 인해 균열 발생을 지연시켰다. RPET 섬유와 PP 섬유를 혼입한 콘크리트 시편의 특성을 비교해보면 두 섬유가 유사하다는 것을 알 수 있다. 따라서 RPET 섬유는 PP 섬유의 대체 재료로서 충분할 뿐만 아니라 폐 PET병을 재활용하고 환경오염을 저감시킨다는 측면에서 친환경적으로 더 뛰어나다는 것을 알 수 있다.

• 한국지반환경공학회 논문집
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• 제19권4호
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• pp.17-26
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• 2018

This study systematically examines the changes in the compressive and tensile strength of soil cement reinforced by natural hair fiber, which is regularly produced from human. Extensive experimental tests of various test specimens have been carried out in a laboratory. Several factors are considered, including the soil type, amount of cement, amount of fiber, fiber length, loading type, and curing age. The test results indicate that both the compressive and tensile strengths are significantly affected by the fiber, either increasing or decreasing depending on the conditions. The increase in tensile strength is significant in the sand-based soil cement due to the tensile resistance of the fiber which is interlocked with the surrounding soil or cement particles. The natural fiber provides a larger strain to failure due to its extensibility, which allows greater deformation. Based on the test results, natural hair fibers can be an effective and environmentally friendly way to improve soil ground subjected to tensile loading, such as an embankment slope, road subgrade, or landfill, thus reducing the cost for cement and waste treatment. The study results provide a useful information of better understanding the mechanical behavior of natural hair fiber in soil cement and the practical use of waste materials in civil engineering. The findings can be practically applied for improving earth structures under tensile loading.

• 한국농공학회논문집
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• 제53권2호
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• pp.35-43
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• 2011

This study aimed to investigate the engineering characteristics of PVA fiber-cement-soil mixture used to prevent or reduce brittle failure of cement-soil mixtures due to the tensile strength increase from the addition of a synthetic fiber. The engineering characteristics of PVA fiber-cement-soil mixtures composed of PVA fiber, soil, and a small amount of cement was analysed on the basis of the compaction test, the unconfined compression test, the tensile strength test, the freezing and thawing test, and the wetting and drying test. The specimens were manufactured with soil, cement and PVA fiber. The cement contents was 2, 4, 6, 8, and 10%, and the fiber contents was 0.4, 0.6, 0.8, and 1.0% by the weight of total dry soil. To investigate the strength characteristics depending on age, each specimen was manufactured after curing at constant temperature and humidity room for 3, 7 and 28 days, after which the engineering characteristics of PVA fiber-cement-soil mixtures were investigated using the unconfined compression test, the tensile strength test, the freezing and thawing test, and the wetting and drying test. The basic data were presented for the application of PVA fiber-cement-soil mixtures as construction materials.

• Journal of the Korean Wood Science and Technology
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• 제50권6호
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• pp.427-435
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• 2022

For effective applicability of reinforced cork, cork composites reinforced with metal, glass fiber, and carbon fiber were developed, and the effects of the reinforcing materials on the mechanical properties of cork composites were investigated. The bending moduli of elasticity (MOE) of cork composites were in the 32.7-35.9 MPa range, while the bending strength values were in the 1.62-1.73 MPa range. The strength performance decreased in the order cork-metal > cork-carbon fiber > cork-glass fiber. The bending MOEs were improved by 29%-41% compared with simple cork boards, while the bending strengths of reinforced cork were 35%-45% higher. The strength performance significantly improved following the incorporation of thin mesh materials into the middle layer of the studied cork composites. The bending strains of the cork composites were remarkably higher compared with oak wood, making them promising for applications that require bending processing, such as curved jointing. The internal bond strengths of the cork composites were 0.26-0.44 MPa, approximately 0.36-0.60 times lower compared with medium-density fiber boards.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.132-133
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• 2020

The aim of this study is to evaluate the combination effect of amorphous steel fiber and polypropylene fiber on spalling of the 150MPa level ultra high strength concrete. Considering spalling has a great relationship with water vapor pressure, this paper is focusing on water vapor pressure. The test specimens were heated accordance with ISO-834 Standard Curve using electric heating furnace, the depth of 10mm water vapor pressure formation was tend to get faster and spalling damage become severe when the mixing proportion of amorphous steel fiber increase. When using ultra high strength concrete reinforced with amorphous steel fiber, further research about proper mixing proportion of polypropylene fiber.