• Journal of the Korea Concrete Institute
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• v.21 no.6
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• pp.705-712
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• 2009

HPFRCCs (high-performance fiber reinforced cementitious composites), which is relatively more ductile and has the characteristic of high toughness with high fiber volume fractions, can be used in structures subjected to extreme loads and exposed to durability problems. In the case of PVA (polyvinyl alcohol) fiber, it is noted by former studies that around 2% fiber volume fractions contributes to the most effective performance at HPFRCCs. In this study, flexural tests were carried out to evaluate the flexural behavior of HPFRCCs and to optimize mix proportions. Two sets of hybrid fiber reinforced high performance specimens with total fiber volume fraction of 2 % were tested: the first set prepared by addition of short and long PVA fibers at different combination of fiber volume fractions, and the second set by addition of steel. In addition, in order to assess the performances of the HPFRCCs against to high strain rates, drop weight tests were conducted. Lastly, the sprayed FRP was applied on the bottom surface of specimens to compare their impact responses with non-reinforcing specimens. The experimental results showed that the specimen prepared with 1.6% short fibers (REC 15) and 0.4% long fiber (RF4000) outperformed the other specimens under flexure, and impact loading.

• Journal of the Korea Concrete Institute
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• v.17 no.2 s.86
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• pp.263-271
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• 2005

HPFRCC(High Performance Fiber Reinforced Cementitious Composite) is a class of FRCCs(Fiber Reinforced Cementitious Composites) that exhibit multiple cracking. Multiple cracking leads to improvement in properties such as ductility, toughness, fracture energy, strain hardening, strain capacity, and deformation capacity under tension, compression, and bending. These improved properties of HPFRCCs have triggered unique and versatile structural applications, including damage reduction, damage tolerance, energy absorption, crack distribution, deformation compatibility, and delamination resistance. These mechanical properties of HPFRCCs become different from the kinds and shapes of used fiber, and it is known that the effective size of fiber in macro crack is different from that in micro crack. This paper reports an experimental findings on the mechanical properties of HPFRCCs reinforced with the micro fiber(PP50, PVA100 and PVA200) and macro fiber(PVA660, SF500). Uniaxial compressive tests and three point bending tests are carried out in order to compare with the mechanical properties of HPFRCCs reinforced with micro fibers or hybrid fibers such as compressive strength, ultimate bending stress, toughness, deformation capacity and crack pattern under bending, etc.,

• 한국방재학회:학술대회논문집
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• 2009.02b
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• pp.129.2-129.2
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• 2009

• Magazine of the Korea Concrete Institute
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• v.18 no.2 s.91
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• pp.56-63
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• 2006

• Proceedings of the KSR Conference
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• 2006.05b
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• pp.551-556
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• 2006

• Computers and Concrete
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• v.26 no.3
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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.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.276-279
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• 2004

Concrete is one of the principal materials for the structure and it is widely used all over the world. but it shows extremely brittle failure under bending and tensile load. Recently to improve such a poor property. High Performance Fiber Reinforced Cementitious Composites (HPFRCC) have been developed. and it are defined by an ultimate strength higher than their first cracking strength and the formation of multiple cracking during the inelastic deformation process. This study is to develop the hybrid HPFRCC with high ductility and strain capacity in bending and tensile load. and the three-point bending test on hybrid HPRFCC reinforced with micro and macro fibers is carried out in this paper. As the results of the bending tests. hybrid HPFRCCs reinforced with PVA40+SF and PVA100+PVA660 showed the high ultimate bending stress, multiple cracks and displacement hardening under bending load.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.401-404
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• 2006

Much of requirements to the civil and building structures have been changed in accordance with the social and economic progress. Ductility of high performance fiber reinforced cementitious composites(HPFRCCs), which exhibit strain hardening and multiple crackling characteristics under the uniaxial tensile stress is drastically improved. In HPFRCC application, PVA fiber has been dominantly used as a reinforcement because of its excellent alkali resistant nature as well as high strength. But the inherent strong hydrophilicity of PVA fiber promotes the moisture absorption in cement matrix and thus it may cause the corrosion of steel structure. Therefore, it is necessary to control the interfacial adhesion of cement composites. In present study, to control the interfacial adhesion of the cementitious composites reinforced by PVA fiber, UV irradiation of the PVA fiber were performed and their effects on the adhesion property and general characteristics were investigated extensively.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.231-234
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• 2005

Steel braced frames retrofit method has been broadly used due to their effectiveness in both light weight and construction periods. However, steel braced frames retrofit method has difficulties in application on the inner frames of buildings to be retrofitted consequently, there have been demands for the braced frames retrofit method that can be broadly and easily applicable to both inner and outer frames of the buildings. The objective of this study is to develop and evaluate the seismic retrofit method applicable to the inner frame also by dividing the reinforcing frames into three unit. From the cyclic test of specimens, the test results dearly showed that steel brace using HPFRCCs and steel bars ensure the better cyclic compressive performance than the normal braced members.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.441-444
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• 2004

This paper presnets the tensile behavior of 8 high performance fiber-reinforced cementitious composites (HPFRCCs) members, each reinforced with one deformed bar 16mm in diameter. The variables included HPFRCC(Ductal, steel cord and polyethylene hybrid fiber, PE fiber) versus normal concrete. Fibers used in HPFRCC significantly increased tensile strength, ductility, and tension stiffening of cementitious materials. For HPFRCC, after first cracking, tensile load continue to rise without fracture localization. Sequentially developed parallel cracks contributed to the inelastic strain at increasing stress level. After yielding of the reinforcing bars, HPFRCC showed increases in loads with increasing strains.