• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.109-115
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• 2015

High performance fiber reinforced cementitious composite (HPFRCC) can provide high fracture energy absorption as well as high strength with high fiber volume fraction. The increased fracture energy helps resisting high frequency loadings, such as earthquake, impact or blast. This study investigates the flexural performance of slurry infiltrated fiber concrete (SIFCON), one of the important HPFRCC, with respect to varying fiber volume fraction. The maximum fiber volume fraction was 8.0 % and reduced to 6.0% by 0.5% and the maximum volume fraction is obtained by packing fibers with simple tapping by hands. The used fiber was a steel fiber with the length 30 mm and the diameter of 0.5 mm. The flexural strengths were 48.7 MPa at 8.0 % and 22.8 MPa at 6.0 %. The measured flexural strength is much higher compared to other cememtitious composite materials but decreased proportional to the fractions. This result implies that for SIFCON considered herein the reduced amount of steel fibers may affect its flexural performance in a negatively way. The flexural toughness, an index to represent the fracture energy absorption, also decreased with the reduced fiber amount.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.521-528
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• 2021

The high-density fiber composite manufacturing method by the extrusion molding method has the characteristic that continuous production is possible, and the product is molded through a mold forming a specific cross-section. OPC is used as a defect material, an appropriate amount of SiO₂ is supplied for CaO reaction activity, and high density and high strength are expressed through steam and autoclave curing. However, due to the use of organic reinforcing fibers, the flame duration exceeds the regulations during the non-combustible performance test, making it difficult to secure performance. In this study, the product was produced by mixing alkali-resistant organic fiber and fly ash having voids as a binder by replacing the existing polypropylene fiber. appeared to be possible.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.133-136
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• 2008

The cost of repairing the deterioration of concrete structures due to corrosion of the reinforcement steel has been the prominent figure in the maintenacne of the reinforced-concrete infrastructures. As an alternative material to steel reinforcement, the use of Glass Fiber Reinforced Polymer (GFRP) bar in concrete is being actively studied for the high resistance of chemical environment and high strength to weight ratio properties of GFRP. However, there remain various aspects of GFRP properties that still need to be studied before the standard design criteria can be established. One of the imminent issues is the bond between GFRP and concrete. In this study, the bond-behavior of GFRP bars in concrete is investigated via the pullout test with varying parameters: surface condition of GFRP bars and concrete compression strength. And the local bond-stress model of GFRP rabars with applying monotonc load was also derived from the present test.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.49-52
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• 2008

The tensile and bond performance of GFRP rebar are different from those of conventional steel reinforcement. It requires some studies on concrete members reinforced with GFRP reinforcing bars to apply it to concrete structures. GFRP has some advantages such as high specific strength, low weight, non-corrosive nature, and disadvantage of larger deflection due to the lower modulus of elasticity than that of steel. Bridge deck is a preferred structure to apply FRP rebars due to the increase of flexural capacity by arching action. This paper focuses on the behavior of concrete bridge deck reinforced with newly developed GFRP rebar. A total of three real size bridge deck specimens were made and tested. Main variable was reinforcement ratio of GFRP rebar. Static test was performed with the load of DB-24 level until failure. Test results were compared and analyzed with ultimate load, deflection behavior.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.101-104
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• 2008

The cost of repairing the deterioration of concrete structures due to corrosion of the reinforcement steel has been the prominent figure in the maintenacne of the reinforced-concrete infrastructures. As an alternative material to steel reinforcement, the use of Fiber Reinforced Polymer (FRP) bar in concrete is being actively studied for the high resistance of chemical environment and high strength to weight ratio properties of FRP. However, there remain various aspects of FRP properties that still need to be studied before the standard design criteria can be established. One of the imminent issues is the bond between FRP and concrete. In this study, the bond-behavior of FRP bars in concrete is investigated via the pullout test with three varying parameters: surface condition of FRP bars, concrete compression strength, and cyclic loading patterns. As a result of experiment, the bond strength of GFRP increased with the concrete compression strength increasing and decreased with applying cyclic load.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2026-2033
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• 2002

The purpose of this study is to investigate the effect of mechanical properties of the FREI using horizontal stiffness and vertical stiffness by experiments. Two kinds of FREI are designed and fabricated. The steel plates of SREI are replaced with fibers in order to reduce the cost of fabrication and installation. At first, the Nylon fiber is adopted as feasibility study of FREI. The experimental results of Nylon FREI and SREI show that the vertical stiffness of Nylon FREI is lower than SREI, and effective damping is two times higher than SREI. Carbon is adopted, by these rusults, as strong reinforcement than Nylon and full scale of carbon FREI was designed and fabricated. By the experimental test results, it is shown that the vertical stiffness of carbon FREI is three times higher than SREI, and two times higher in effective damping. As a result, the proposed FREI can replace the SREI as a seismic isolator.

• Journal of the Korean Geosynthetics Society
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• v.7 no.2
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• pp.41-47
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• 2008

This paper describes the results of model experiments in the laboratory, which were conducted to assess the behavior characteristics of geosynthetic reinforced soil walls according to different surcharge loads and reinforcement types. The model walls were built in the box having dimension, 100 cm tall, 140 cm long, and 100cm wide. Three types of geosynthetics, geonet, geogrid A and geogrid B, are used as the reinforcements. Decomposed granite soil (SM) was used as a backfill material. Seven model walls are constructed and tested. After the construction of the model wall, the LVDTs are installed to obtain the displacements of the wall face. As the results of the model tests, the maximum horizontal displacements of the model walls occurred due to uniform surcharge pressure were measured at the 0.7H from the bottom of the wall. The more the reinforcement strength increases, the more the wall displacements decrease, and also the reduction ratio of the wall displacement decrease with increasing the surcharge pressure.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.2
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• pp.203-209
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• 2010

In this study, the fatigue characteristics and life of a woven glass fabric/epoxy laminate composite applied to railway vehicles was evaluated. The fatigue test was conducted using a tension-tension load with a stress ratio R of 0.1 and frequency of 5 Hz. Two types of woven glass fabric/epoxy laminate composite was used in the fatigue test: with and without carbon/epoxy ply reinforcement. In addition, the fatigue life of the woven glass fabric/epoxy laminate composite was compared with that of aluminum 6005, which is used in the car body and underframe structures of railway vehicles. The test results showed that the failure strength and life of the woven glass fabric/epoxy laminate composite reinforced with three carbon/epoxy plies had a remarkable improvement compared with that of the bare specimen without reinforcement.

• Journal of the Korea Concrete Institute
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• v.25 no.5
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• pp.477-484
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• 2013

In this study, eleven reinforced concrete beams, ground granulated blast furnace slag, replacing recycled coarse aggregate (BRS series) and recycled coarse aggregate with steel fiber (BSRS series), and standard specimen (BSS) were constructed and tested under monotonic loading. Experimental programs were carried out to improve and evaluate the shear performance of such test specimens, such as the load-displacement, the failure mode and the maximum load carrying capacity. All the specimens were modeled in 1/2 scale-down size. Test results showed that test specimens (BSRS Series) was increased the compressive strength by 9%, the maximum load carrying capacity by 1~6% and the ductility capacity by 1.02~1.13 times in comparison with the standard specimen (BSS). And the specimens (BSRS Series) showed enough ductile behavior and stable flexural failure.