• Title, Summary, Keyword: 강섬유 보강 콘크리트

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Slump and Mechanical Properties of Hybrid Steel-PVA Fiber Reinforced Concrete (강섬유와 PVA 섬유로 하이브리드 보강된 콘크리트의 슬럼프 및 역학적 특성)

  • Yang, Keun-Hyeok
    • 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.

Compressive Behavior of Hybrid Steel Fiber Reinforced Ultra-High Performance Concrete (하이브리드 강섬유 보강 초고성능 콘크리트의 압축거동)

  • Lim, Woo-Young;Hong, Sung-Gul
    • 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.

Estimation of The Basic Properties of Two-Lift Concrete Pavement to Apply Korea Condition (이층 포설 콘크리트 포장의 국내 적용을 위한 강섬유 보강 콘크리트 기초 물성평가)

  • Won, Hong-Sang;Ryu, Sung-Woo;Hong, Jong-Yong;Cho, Yoon-Ho
    • 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.

Evaluation of Mechanical Properties and Crack Resistant Performance in Concrete with Steel Fiber Reinforcement and CSA Expansive Admixture (CSA 팽창재를 혼입한 강섬유 보강 콘크리트의 역학적 성능 및 균열 저항성능 평가)

  • Choi, Se-Jin;Park, Ki-Tae;Kwon, Seung-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.1
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    • pp.75-83
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    • 2014
  • In order to prevent brittle failure of concrete, steel fiber reinforcement is effective composite material. However ductility of steel fiber reinforced concrete may be limited due to shrinkage caused by large content of cement binder. Chemical prestressing for steel fiber reinforcement in cement matrix can be induced through expansive admixture and this can increase reinforcing effect of steel fiber. In this study, mechanical performances in concrete with CSA (Calcium sulfoaluminate) expansive admixture and steel fiber reinforcement are evaluated. For this work, steel fiber reinforcement of 1 and 2% of volume ratio and CSA expansive admixture of 10% weight ratio of cement are added in concrete. Mechanical and fracture properties are evaluated in concrete with steel fiber reinforcement and CSA expansive admixture. CSA concrete with steel fiber reinforcement shows increase in tensile strength, initial cracking load, and ductility performance like enlarged fracture energy after cracking. With appropriate using expansive admixture and optimum ratio of steel fiber reinforcement, their interactive action can effectively improve brittle behavior in concrete.

An Experimental Study on the Fracture Energy of Steel Fiber Reinforced Concrete Structures by the Effects of Fiber Contents (강섬유 혼입량에 의한 강섬유보강콘크리트의 파괴에너지에 관한 실험적 연구)

  • 장동일;채원규;정원우;손영환
    • Magazine of the Korea Concrete Institute
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    • v.3 no.4
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    • pp.79-88
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    • 1991
  • In this study, fracture tests were carried out in order to investigate the fracture behavior of SFRC(Steel Fiber Peinforced Concrete) with initial cracks. The relationships between loading. strain, mld-span deflections and CMOD(Crack Mouth Opening Displacement) of the beams were observed under the three point loading system. The effect of the fiber content and the initial crack ratio on the concrete fracture behavior were studied and the fracture toughness, the critical energy release ratio and the fracture energy were also calcul ated from the test results. From the test results, it was known that when the fiber contents are between 0.5% and 1.0%, and 1.5% the average fracture energy of SFRC specimens is about 7~10 times. and about 15 times better than that of the plam concrete specimens respectively.ively.

Flexural Performance Characteristics of Amorphous Steel Fiber-Reinforced Concrete (비정질 강섬유보강콘크리트의 휨성능 특성)

  • Ku, Dong-Oh;Kim, Seon-Du;Kim, Hee-Seung;Choi, Kyoung-Kyu
    • Journal of the Korea Concrete Institute
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    • v.26 no.4
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    • pp.483-489
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    • 2014
  • In this study, the flexural test of amorphous steel fiber-reinforced concrete was performed according to ASTM C 1609 to investigate its flexural performances. The amorphous steel fibers have different configurations from conventional steel fibers : thinner sections and coarser surfaces. Primary test parameters are fiber type (amorphous and conventional steel fibers), concrete compressive strength (27 and 50 MPa), and fiber volume fraction (0.25, 0.50, and 0.75%). Based on the test results, flexural strength and flexural toughness of the amorphous and conventional steel fiber-reinforced concrete were investigated. The results showed that the addition of the amorphous steel fibers into concrete could enhance both flexural strength and toughness while the addition of the conventional steel fibers into concrete was mainly effective to increase the flexural toughness.

Evaluation of Shear Strength in SFRC Beam without Stirrups Considering Steel Fiber Strengthening Factor (강섬유 보강계수를 고려한 전단보강 되지 않은 SFRC 보의 전단내력 평가)

  • Lee, Hyun-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.8 no.2
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    • pp.213-220
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    • 2004
  • The purpose of this study is to evaluate the shear strength of SFRC beam that has no stirrups by steel fiber strengthening factor. To achieve the goal of this study, two stage investigation, which is material and member level, is studied with literature and experimental side. From the reviewing of previous researches and analyzing of material and member test results, strengthening parameter of SFRC is defined as steel fiber coefficient. Based on above results, steel fiber strengthening factor is proposed. And by reviewing the proposed equation of shear strength estimation, equation of Shin was well estimated the shear strength of SFRC beams. Therefore, shear strength equation of SFRC, which is composed by Shin's Eq. and steel fiber strengthening factor, is proposed by regression analysis of test results.

Flexural Behavior of Ultra High Performance Fiber Reinforced Concrete Segmental Box Girder (초고강도 섬유보강 콘크리트 분절형 박스 거더의 휨거동)

  • Guo, Qingyong;Han, Sang-Mook
    • Journal of the Korea Concrete Institute
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    • v.26 no.2
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    • pp.109-116
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    • 2014
  • The flexural behavior test of UHPC segmental box girder which has 160 MPa compressive strength and 15.4 m length was carried out. The effect of steel fibers in combination with reinforcing bars on improving the ductile performance of UHPC box girder was evaluated by comparing the flexural behavior of the UHPC segmental box girders made by the two kinds of mixing portion. The test variables are volume fraction of steel fibers and the arrangement of reinforcing bars. The behavior of UHPC box girder BF2 composed of 1% volume fraction of steel fibers and longitudinal reinforcing bars in web and upper flange with stirrup showed the similar ductile behavior with the girder BF1 composed of 2% volume fraction without stirrup in elastic stress region. But BF1 had the better stiffness and showed the more ductile behavior in inelastic stress region. Segmental interfaces of UHPC box girder have not any crack and slide until the final flexural collapse load.

Effects of Aggregate Size and Steel Fiber Volume Fraction on Compressive Behaviors of High-Strength Concrete (골재크기 및 섬유혼입률에 따른 강섬유 보강 고강도 콘크리트의 압축거동)

  • Ahn, Kyung-Lim;Jang, Seok-Joon;Jang, Sang-Hyeok;Yun, Hyun-Do
    • Journal of the Korea Concrete Institute
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    • v.27 no.3
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    • pp.229-236
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    • 2015
  • This paper describes the effect of aggregate size on compressive behavior of high-strength steel fiber reinforced concrete. The Specified compression strength is 60 MPa and the range of fiber volume fraction is 0~2%. The main variable is the aggregate size, which was used for the aggregate size of 8 and 20 mm. So, ten concrete mixtures were prepared and tested to evaluate the fresh and hardened properties of SFRC at curing ages (7, 14, 28, 56 and 91 days), respectively. Items estimated in this study are the fresh properties (air contents, slump), hardened properties (compressive strength, modulus of elasticity, post-peak response and compressive toughness). As a result, the aggregate size has little effect on the compressive strength and modulus of elasticity. On the other hand, the ductile behavior was shown after post peak and the compressive toughness was increasing as decreasing the aggregate size. These effects are clearly represented in the fiber volume fraction 2%, which are the point appeared fiber ball. It is considered that the decreasing the aggregate size has effect on the fiber dispersibility.

Strength and Deformation Characteristics of Steel Fiber Reinforced Columns (강섬유 보강 기둥의 강도 및 변형 특성)

  • 장극관;이현호;양승호
    • Journal of the Korea Concrete Institute
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    • v.14 no.1
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    • pp.49-57
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    • 2002
  • As composite materials, the addition of steel fiber with concrete significant)y improves the engineering properties of structural members, notably shear strength and ductility. Flexural strength, fatigue strength, and the capacity to resist cracking are also enhanced. Especially the strengthening effect of steel fiber in shear is to prevent the brittle shear failure. In this study, shear-strengthening effect of steel fiber in RC short columns were investigated from the literature surveys and 10th specimem's member test results. From the test results, following conclusions can be made; the maximum enhancement of shear-strengthening effect can be achieved at about 1.5 % of steel fiber contents, shear strength and ductility capacity were improved remarkably in comparison to stiffness and energy dissipation capacity in steel fiber reinforced concrete.