• Title/Summary/Keyword: 고인성 섬유보강 콘크리트

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Static and Fatigue Flexural Tests of Ductile High-performance Fiber Reinforced Cementitious Composites (고인성 섬유보강 콘크리트의 정적 및 피로 휨시험)

  • Shin, Kyung-Joon;Lee, Do-Keun;Lee, Kyoung-Chan;Kim, Sung-Il
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.4
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    • pp.602-608
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    • 2021
  • Recently, research and development has been conducted to impart high performance and functionality to concrete materials by mixing various reinforcing materials into the matrix. Ductile fiber reinforced concrete using a large amount of fibers shows a distributed multiple cracking behavior, and various studies are being conducted on this material. However, research is focused on static behavioral analysis but studies on cyclic behaviors are not sufficient. In this study, beams were made of ductile fiber reinforced concrete with various fiber contents, and static and fatigue flexural tests were performed. As a result, the effect of fiber content on the flexural behavior was analyzed. Also, the applied load level and fatigue life relationship of ductile fiber reinforced concrete was proposed. Concrete with high ductile property could be achieved with a fiber content of 2%. When 0.5% fiber was more added, the maximum flexural strength was similar, but the flexural toughness is nearly doubled. On the other hand, there was no significant difference in the fatigue life of these two mixtures.

Flexural toughness density of High Performance Fiber Reinforced Cementitious Composites (고인성 섬유보강 시멘트 복합재료의 휨인성 밀도)

  • Kim, Dong-Joo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.401-402
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    • 2010
  • This research initially suggest flexural toughness density as a key parameter describing energy absorption capacity of High Performance Fiber Reinforced Cementitious Composites [HPFRCC] regardless of the size of specimen. Two types of high strength steel fibers, Hooked and Twisted fiber, were used in two types of flexural specimen ($100{\times}100{\times}350mm^3$ and $150{\times}150{\times}500mm^3$) to estimate and validate the flexural toughness density.

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Assessment of the Damage in High Performance Fiber-Reinforced Cement Composite under Compressive Loading Using Acoustic Emission (AE기법에 의한 압축력을 받는 고인성 섬유보강 시멘트 복합체의 손상 평가)

  • Kim, Sun-Woo;Yun, Hyun-Do
    • Journal of the Korea Concrete Institute
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    • v.21 no.5
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    • pp.589-597
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    • 2009
  • High Performance Fiber-reinforced Cement Composite (HPFRCC) shows the multiple crack and damage tolerance capacity due to the interfacial bonding of the fibers to the cement matrix. For practical application, it is needed to investigate the fractural behavior of HPFRCC and understand the micro-mechanism of cement matrix with reinforcing fiber. This study is devoted to the investigation of the AE signals in HPFRCC under monotonic and cyclic uniaxial compressive loading, and total four series were tested. The major experimental parameters include the type and volume fraction of fiber (PE, PVA, SC), the hybrid type and loading pattern. The test results showed that the damage progress by compressive behavior of the HPFRCC is a characteristic for the hybrid fiber type and volume fraction. It is found from acoustic emission (AE) parameter value, that the second and third compressive load cycles resulted in successive decrease of the amplitude as compared with the first compressive load cycle. Also, the AE Kaiser effect existed in HPFRCC specimens up to 80% of its ultimate strength. These observations suggested that the AE Kaiser effect has good potential to be used as a new tool to monitor the loading history of HPFRCC.

High Ductile Fiber Reinforced Concrete with Micro Fibers (마이크로 섬유를 혼입한 고인성 섬유 보강 콘크리트)

  • Shin, Kyung-Joon;Lee, Seong-Cheol;Kim, Yun-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.2
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    • pp.92-98
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    • 2019
  • In general, high strength and high performance fiber reinforced cement composites exclude coarse aggregates basically in order to have homogeneous distributions of material properties. However, these fiber-reinforced cement mortar without coarse aggregate have a tenancy that the modulus of elasticity is low and the unit weight of cement is high, resulting in low economic efficiency. Therefore, in this study, the development of high ductile fiber - reinforced concrete was conducted, which has the adequate level of coarse aggregate but still retains the high flexural toughness and strength and also has the crack - distributing performance. Experimental study was carried out by using the amount of coarse aggregate as an experimental parameter. The results showed that the best flexural toughness and crack dispersion characteristics was obtained when the coarse aggregate was added at 25% by weight of the fine aggregate to the typical mixtures of high ductile cement mortar. PVA fiber was effective in crack distribution and ductility enhancement, and steel fiber was effective in strengthening flexural strength rather than crack distribution.

Effect of Reinforcing Fiber Types on Lap Splice Performance of High Performance Fiber Reinforced Cementitious Composite(HPFRCC) (보강 섬유 종류에 따른 고인성 시멘트 복합체내에서 철근의 겹침 이음 성능)

  • Jeon, Esther;Yun, Hyun-Do
    • Journal of the Korea Concrete Institute
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    • v.19 no.2
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    • pp.153-161
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    • 2007
  • This paper investigates the lap splice performance of structural steel bars embedded in high performance fiber reinforced cementitious composite(HPFRCC) with various matrix ductilities. Matrix ductility is governed fiber type and fiber volume fraction. Fiber types were polypropylene(PP), polyethylene(PE) and hybrid fiber[polyethylene fiber+steel cord(PE+SC)]. The lap splice length$(l_d)$ was calculated according to the relevant ACI code requirements for reinforcing bars in normal concrete. As the result of tests, lap splice strength of HPFRCC using PE1.5 and hybrid fiber increased by up to $82{\sim}91$ percent more than that of concrete. Splice strength and energy absorption capacity of PE0.75+SC0.75 or PE1.5(fiber volume fraction 1.5%) specimen increased more than that of PP2.0(fiber volume fraction 2.0%) specimen. Therefore lap splice performance depends on fiber tensile strength and Young's modulus more than fiber volume fraction. Also, HPFRCC appear multiple crack and ductile postpeak behavior due to bridging of fiber in cementitious composite.

Evaluation of Seismic Performance of High Strength Reinforced Concrete Exterior Beam-Column Joints Using High Ductile Fiber-Reinforced Mortar (고인성섬유 복합모르타르를 활용한 고강도 철근콘크리트 외부 보-기둥 접합부의 내진성능평가)

  • Ha, Gee-Joo;Shin, Jong-Hak
    • Journal of the Korea Concrete Institute
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    • v.25 no.4
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    • pp.419-428
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    • 2013
  • In this study, experimental research was carried out to evaluate the constructability and seismic performance of high strength R/C exterior beam-column joints regions, with or without the shear reinforcement, using high ductile fiber-reinforced mortar. Five specimens of retrofitted the exterior beam-column joint regions using high ductile fiber-reinforced mortar are constructed and tested for their retrofit performances. Specimens designed by retrofitting the exterior beam-column joint regions (BCJNSP series) of existing reinforced concrete building showed a stable mode of failure and an increased its maximum load-carrying capacity by 1.09~2.03 times in comparison with specimen of BCJNS due to the effect of enhancing dispersion of crack control at the time of initial loading and bridging of fiber from retrofitting new high ductile materials during testing. Specimens of BCJNSP series attained its maximum load carrying capacity by 0.92~0.96 times and increased its energy dissipation capacity by 1.62 times when compared to standard specimen of BCJC with a displacement ductility of 4.

Tension Stiffening of Reinforced High Performance Fiber Reinforced Cementitious Composites (HPFRCC) (철근 보강 고성능 섬유보강 콘크리트의 인장 강성)

  • Lee, Seong-Cheol;Kim, Jae-Hwa;Cho, Jae-Yeol;Shin, Kyung-Joon
    • Journal of the Korea Concrete Institute
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    • v.22 no.6
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    • pp.859-866
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    • 2010
  • To overcome weak and brittle tensile characteristics of concrete, many studies have been conducted on fiber reinforced concrete (FRC). Recently, high performance fiber reinforced cementitious composites (HPFRCC), which shows strain hardening behavior, has been actively investigated. However, most of the studies focused on the material behavior of HPFRCC itself. Only a few studies have been conducted on the tensile behavior of HPFRCC with steel reinforcement. Therefore, a tension stiffening test for HPFRCC members has been conducted in this study in order to investigate the effect of a reinforcing bar on the tensile behavior of HPFRCC. Tensile stress-strain relationship of HPFRCC has been derived from the tests. The HPFRCC resisted tensile stress continuously from the first cracking to the yield of reinforcing bar. Through the comparison with the tensile behavior of HPFRCC members without a reinforcement, it was shown the tensile strength and capacity of HPFRCC were reduced due to the combined effect of the high shrinkage of HPFRCC, restraining effect of steel reinforcement, and the strain hardening behavior of HPFRCC. It is expected that the tension stiffening test results can be useful for an application of HPFRCC with steel reinforcement as structural members.

An Experimental Study for Bond Stress between DFRCC and Carbon FRP Plank Used as a Permanent Formwork (영구거푸집으로 활용한 탄소섬유 FRP 판과 DFRCC 사이의 부착응력에 관한 실험적 연구)

  • Park, Chan-Young;Yoo, Seung-Woon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.6
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    • pp.1687-1694
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    • 2014
  • Recently FRP of carbon fibers is utilized as a repairing and reinforcing material for concrete structures. In this study, the bond performance between CFRP planks and ductile fiber reinforced cementitious composites was evaluated in order to develop a new system of concrete bridge deck to take advantage of the FRP planks of carbon fiber using as a permanent formwork. In order to strengthen the bonding between the FRP and cast-in-place concrete, an epoxy resin circulated in the market generally was fitted with a silica sand. The bond stress of ordinary concrete appeared in 2.11~5.43MPa and the bond stress of ductile fiber reinforced cementitious composites DC1 (RF4000) and DC2 (PP) respectively were 3.91~5.60MPa, 2.92~5.21MPa and the average bond stress of DC3 (RF4000+RSC15) and DC4 (PP+RSC15) were 4.80~5.58MPa, 5.57~5.89MPa.