• Journal of the Korea Concrete Institute
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• v.22 no.5
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• pp.651-658
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• 2010

Sixteen concrete mixes reinforced with hybrid steel-polybinyl alcohol (PVA) fibers and a control concrete mix with no fiber were tested in order to examine the effect of the micro and macro fibers on the slump and different mechanical properties of concrete. Main variables investigated were length and volume fraction of steel and PVA fibers. The measured mechanical properties of hybrid fiber reinforced concrete were analyzed using the fiber reinforcing index and compared with those recorded from monolithic steel or PVA fiber reinforced concrete. The initial slump of hybrid fiber reinforced concrete decreased with the increase of the aspect ratio and the volume fraction of fibers. In addition, splitting tensile strength, modui of rupture and elasticity, and flexural toughness index of concrete increased with the increase of the fiber reinforcement index. Modulus of rupture and flexural toughness index of hybrid fiber reinforced concrete were higher than those of monolithic fiber reinforced concrete, though the total volume fraction of hybrid fibers was lower than that of monolithic fiber. For enhancing the flexural toughness index of hybrid fiber reinforced concrete, using the steel fiber of 60 mm length was more effective than using the steel fibers combined with 60 mm and 30 mm lengths.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.225-232
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• 2014

This paper concerns the mechanical properties of recycled plastic fiber-reinforced concrete. It presents experimental research results of recycled fiber-reinforced concrete with fiber volume fractions of 0, 0.5, 1.0, 1.5, and 2%. Experiments were performed to measure mechanical properties such as compressive strength, elastic modulus, tensile strength, and length changes. The results show that both compressive strength and elastic modulus decreased as fiber volume fraction increased. In addition, the experimental results show that recycled fiber-reinforced concrete is in favor of split tensile strength, flexural tensile strength, characteristic regarding crack mouth opening displacement, and length changes. The results of this study can be used to provide realistic information for modeling of mechanical properties in recycled plastic fiber-reinforced concrete in the future.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.275-282
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• 2009

The effects of surface treatment method of reinforcing fiber on the bonding strength between carbon fiber reinforced polymer rebar (CFRP rebar) and high strength concrete have been evaluated in this study. The structural PVA fiber is coated with a proprietary hydrophobicoiling agent and crimped type polyolefin based structural synthetic fiber is deformed with a geometrical modification were used for the reinforcing fiber. The compressive tests have been performed to evaluate the strength property of high strength concrete depending on the surface treatment method of fiber. The bonding property between the high strength concrete and the CFRP rebar was evaluated by means of direct bonding test. The test results indicated that the surface treatment method of fiber effect on the bonding behavior of high strength concrete and CFRP rebar. Also, as the development and propagation of splitting cracks were controled by adding fibers into the high strength concrete, the bonding behavior, bond strength and relative bonding strength of CFRP rebar and high strength concrete were significantly improved.

• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.213-221
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• 2016

Uniaxial compression tests for ultra-high performance hybrid steel fiber reinforced concrete (UHPC) were performed to evaluate the compressive behavior of UHPC. The UHPC for testing contains hybrid steel fibers with a predetermined ratio using a length of 19 mm and 16 mm straight typed steel fibers. Test parameter was determined as a fiber volume ratio to investigate the effect of fiber volume ratio on the strength and secant modulus of elasticity. Test results showed that the compressive strength and elastic modulus of UHPC increased with increasing the fiber volume ratio. Based on the test results, the compressive strength and modulus of elasticity equations were proposed as function of the compressive strength of unreinforced and fiber reinforced UHPC, respectively. The simplified equations for predicting the mechanical properties of the UHPC were a good agreement with the test data. The proposed equations are expected to be applied to the SFRC and UHPC with steel fibers.

• Journal of the Korea Concrete Institute
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• v.19 no.2
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• pp.145-151
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• 2007

The shear failure modes of FRP strengthened concrete beams are quite different to those of the beams strengthened with steel stirrups. When the beams are externally wrapped with FRP composites, many beams fail in shear due to concrete crushing before the FRP reaches its rupture strain. In order to predict the shear strength of such beams, the effective strain of the FRP must be blown. This paper presents the results of an experimental study on the performance of reinforced concrete beams externally wrapped with FRP composites and infernally reinforced with steel stirrups. The main parameters of the tests were FRP reinforcement ratio, the type of fiber material (carbon or glass) and configuration (continues sheets or strips). The experimentally observed effective strain of the FRP was compared with the strain calculated using a proposed method.

• Magazine of the Korea Concrete Institute
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• v.4 no.2
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• pp.103-110
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• 1992

본 연구는 인성지수에 의하여 섬유보강 콘크리트의 인성을 평가하는 기존의 여러 가지 방법을 검토하는, 하중-처짐곡선에서 초기균열시까지의 여러 가지 다른 곱으로 나타내어지는 방법의 불합리성을 지적하였다. 이를 위하여 본 연구에서는 유효인성이라고 부르는 새로운 방법을 강섬유 보강콘크리트의 인성을 평가하는데 제안하였다. 이는 초기균열을 가진 3점 휨강도 시험에 의한 하중-처짐곡선에서 지간의 1/150까지의 면적을 ligament면적으로 나눈값으로 나타낸다. 이 방법을 사용하여 강섬유 보강 고강도 콘크리트 인성특성을 검토한 결과 기존의 방법보다 더 효과적으로 인성을 평가할 수 있었다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.797-800
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• 2008

To decrease the usage of cement, the pozzolan reaction materials are used as a mineral admixture. Hwang Toh which is broadly deposited in Korea is well known as a environment friendly material and the activated Hwang Toh which has the property of pozzolan reaction is practically used as a mineral admixture of concrete. PET fiber which is made by recycled PET bottle controls micro crack in concrete. But the study about concrete mixed with reinforcing fiber is not enough and the property of Hwang Toh concrete mixed with PET fiber is more complicated case. So this study performed drying shrinkage experiment to analyse mechanical property of Hwang Toh concrete mixed with PET fiber.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.2
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• pp.51-58
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• 2008

This study is to investigate the ultimate shear load of prestressed girder made of Ultra High Performance Fiber Reinforced Concrete (UHPFRC). Nine girders were tested until failure in shear. An analytical model to predict the ultimate shear load was formulated based on the Two Bounds Theory. A fiber reinforcing model was constituted based on the random assumption of steel fiber uniform distribution. The predicted values were compared with the conventional predictions and the test results. The proposed equations for computing the ultimate shear strength can be used for the ultimate failure status analysis, which could also be utilized for numerical limit analysis of prestressed UHPFRC girder. The established fiber reinforcing theoretical model can also be a reference for micro-mechanics analysis of UHPFRC.

• Journal of the Society of Disaster Information
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• v.13 no.2
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• pp.213-220
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• 2017

Organic fiber reinforced concrete is applicable to many applications for construction material. In general, organic fibers have low tensile strength and elastic modulus, but they have many advantages such as high crack resistance, impact resistance, chemical resistance, flexural behavior and corrosion resistance. In this study, hybrid organic fibers were prepared by mixing polyamide (PA) fibers and high strength polyester (PET) fibers. Then, flexural performance test of fiber reinforced concrete containing hybrid organic fiber was performed. The energy absorption capacity of the hybrid organic fiber reinforced concrete was evaluated.

• International Journal of Highway Engineering
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• v.12 no.1
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• pp.47-54
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• 2010

This study had a focus on investigating technical validity of Two-Lift Concrete Pavements which had never been constructed in Korea in order to olve the problem of existing concrete pavements. This study found out the application of Steel Fiber Reinforced Concrete (SFRC) which was one of ew techniques. Also, optimal steel fiber contents and pavement thickness were determined. This study also measured compressive strengths, lexural strengths, toughness indexes, tensile strengths and fatigue strengths to estimate the performance of SFRC of according to results of aboratory experiments, slumps and air contents of concrete specimens the standards satisfied and compressive strengths to open traffic. At bending ests, Toughness Index of SFRC increased but flexural strength didn’'t increase as compared with non-steel fiber concretes. And, energy absorption of SFRC was very good and SFRC showed improvement in freezing and thawing resistances. To complete this research, we will evaluate the pplication methods and performance of SFRC at field section.