• Journal of the Society of Disaster Information
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• v.11 no.4
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• pp.607-614
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• 2015

This study evaluated the flexural performance of steel and PP fiber reinfroced shotcrete using round panel test according to ASTM that can consider the actual stress of fiber reinforced shotcrete in tunnel and under ground structures. The results of round panel test are converted to the square panel test results according to the EFNARC. The energy absorptions of each fiber reinforced shotcrete were classified according to the EFNARC toughness classification. Test results show that the PP fiber reinforced shotcrete has better flexural performance compared with the steel fiber reinforced shotcrete.

• Polymer(Korea)
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• v.32 no.1
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• pp.7-12
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• 2008

We confirmed that poly (ethylene terephthalate) (PET) fiber had the possibility to improve the mechanical properties of polypropylene (PP) by fabricating PP/PET fiber composites because PET enhanced mechanical properties and higher melting temperature than PP. But lower compatibility of between PP and PET fibers induced poor mechanical properties of PP/PET fiber composites in spite of incorporating PP-g-MAH as compatibilizer. To solve these problems of PP/PET fiber composites, we carried out a surface treatment on PET fiber using NaOH solution and Prepared PP/PET fiber composites with good mechanical properties by adding PP-g-MAH as a compatibilizer Then the behavior of the mechanical properties was correlated with the results obtained from SEM and IR spectroscopy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.2
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• pp.83-90
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• 2006

A spalling is defined as the damages of concrete exposed to high temperature during the fire by causing cracks and localized bursting of small pieces of concrete. It is reported that spalling is caused by the vapor pressure and polypropylene(PP) fiber has an important role in protecting from spalling. The characteristics of fire resistance of high-strength reinforced concrete columns with various concrete strength and various contents of PP fiber were investigated in this study. In results, the ratio of unstressed residual strength of columns increases as the concrete strength increases and the ratio of unstressed residual strength of columns exposed to fire decreases as the content of PP fiber increases from 0% to 0.2%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4A
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• pp.391-398
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• 2010

The fire performance of RC slabs with half-depth precast panel after exposure to the ISO-834 fire standard without loading has been experimentally investigated. During heating, according to the ISO 834 fire curve, concrete spalling was observed for concrete without PP(polypropylene) fibers. No spalling occurred when heating concrete containing PP fibers. The maximum temperature of RC slabs with PP fibers with half-depth precast panel was lower than that of concrete without PP fibers. The ultimate load after cooling of the RC slabs that were not loaded during the furnace tests was evaluated by means of 3 points bending tests. The ultimate load of the RC slabs without PP fibers showed a considerable reduction (around 32.5%) of the ultimate load after cooling if compared with of RC slabs with PP fibers. The ultimate load of the RC slabs with half-depth precast panel with PP fibers is higher than that of a full-depth RC slabs with PP fibers. Also, the addition of PP fibers and the use of half-depth precast panel improve fire resistance.

• Journal of the Korean Geosynthetics Society
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• v.14 no.4
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• pp.105-115
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• 2015

In this study, to understand mechanical characteristic of hybrid reinforced concrete by PVA-fiber 6 mm and PP-fiber 50 mm, which are organic fiber replaced macro-fiber with PP-fiber, four mixed Hybrid Organic Fibers Reinforced Concrete (HFRC) is compared with one mixed plain concrete without fiber reinforcement. Volume portion of the fibers are limited under one percent. The result presents that hybrid reinforcement of the organic fibers cannot maximize stiffness and ductility behavior of the steel fiber reinforcement. however, in comparison to plain concrete, it is confirmed that meaningful relation between toughness index and equivalent flexural strength with advanced ductility behavior. Also, in the case of concrete hybrid reinforced by organic fiber, when the volume portion of the fiber increases, ductility also increases. PP-fiber, which is macro fiber, has more effect on the flexural behavior of concrete than PVA-fiber, which is micro fiber, does. The result also shows that it decrease chloride penetration in chloride penetration test.

• Fire Science and Engineering
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• v.23 no.4
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• pp.7-12
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• 2009

As the concrete strength increases the degree of damage caused by the spalling becomes more serious because of the permeability. It is reported that the polypropylene (PP) fiber has an important role in protecting concrete from spalling. However, the excessive usage of PP fiber would not useful in spalling control and would decrease the workability of ultra high strength concrete. The high-temperature behaviors of high-strength reinforced concrete columns with various dosage of PP fibers and three types of fire endurance fibers were observed this study. In results, the ratio of unstressed residual strength of columns, in case of concrete strength 60MPa, increases as the dosage of PP fiber increases from 0% to 0.2%, however, the effect of fiber dosage on residual strength of column barely changes above 0.2% and in case of concrete strength 120MPa, PVA fiber is the most suitable fire endurance fiber in accounting fire endurance performance and workability.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.424-432
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• 1996

The fiber reinforced thermoplastic composites(FRTP) were prepared with polypropylene fiber(PPF) as matrix and vinylon(VF), Aramid(KF) or nylon fiber(PAF) as reinforcing materials using the integrated fiber mixing apparatus. The composite sheets were prepared by compression molding and their impact and morphological properties were characterized. VF/PP system showed the maximum value in Izod impact strength, while KF/PP system showed the maximum value in high rate impact properties. Ductility Index(DI) order was VF/PP>KF/PP>PAF/PP. A maximum DI for VF/PP, 2.43, was obtained when the weight fraction of VF was 20%. The optimum amount of the reinforcing organic fiber was found to be 20~30%. As a result, it is concluded that VF/PP system has better interfacial adhesion properties than either KF/PP or PAF/PP.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.3
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• pp.433-452
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• 2019

This study deals with shotcrete reinforcing performance according to the amount of synthetic fiber (PP fiber) and proper evaluation method. The shotcrete compressive strength, flexural strength and flexural toughness were tested by setting the mixing amounts of steel fiber ($37.0kg/m^3$) and synthetic fiber (PP fiber) as parameters ($5.0kg/m^3$, $7.0kg/m^3$ and $9.0kg/m^3$). Particularly, circular panel flexural toughness test (Road and Traffic Authority, RTA) was performed to evaluate the shotcrete energy absorption capacity. As a result, the compressive strength and the bending strength of the steel fiber reinforced shotcrete were large, but the flexural toughness of the synthetic fibe (PP fiber) reinforced shotcrete was large. Therefore, synthetic fiber (PP fiber) reinforced shotcrete is considered to have a reinforcing effect comparable to that of steel fiber reinforced shotcrete. Analysis of the relationship between the flexural toughness and the energy absorption capacity of synthetic fiber (PP fiber) reinforced shotcrete revealed that the energy absorbing ability is exhibited at a flexural toughness lower than the allowable standard (3.0 MPa). (Class A: 2.55 MPa = 202J, Class B: 2.72 MPa = 282J, Class C: 3.07 MPa = 403J). As a result of this study, it can be concluded that the actual shotcrete support performance can be evaluated by evaluating the support performance of the shotcrete measured at less than the allowable standard (3.0 MPa) at the actual tunnel site.

• Journal of the Korea Institute of Building Construction
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• v.9 no.6
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• pp.113-119
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• 2009

This study is to investigate the fundamental and fireproof qualities of high strength concrete corresponding to changes in the curing factors and the PP fiber ratio. The results were as follows. For the fundamental characteristics of concrete, the fluidity was reduced in proportion to the increase in the PP fiber ratio. The compressive strength was somewhat reduced according to an increase in the PP fiber ratio. However, it had the high strength scope of more than 60 MPa at 7 days and of more than 90 MPa at 28 days. On the spalling mechanism followed by changes of the water content ratio, spalling was prevented in all combinations, except the specimen without PP fiber and subjected to 3.0% of moisture contents. When spalling was prevented at that time, the residual compressive strength ratio was 22%~41% and the mass reduction ratio was 5%~7%, which was relatively favorable. As the spalling mechanism corresponds to changes in the curing method, spalling was prevented in concrete with a PP fiber mixing ratio of more than 0.05% in the event of standard curing, and in concrete with a PP fiber mixing ratio of more than 0.10% in the case of steam curing and autoclave curing. In these cases, when spalling was prevented, the residual compressive strength ratio was 23~42% and the mass reduction ratio was 7~11%. In these results, the ease of spalling prevention in high strength concrete was inversely proportional to the water content ratio. Depending on the curing method, spalling was prevented in concrete with over 0.05% PP fiber with standard curing and in concrete with over 0.1% PP fiber with steam curing and autoclave curing.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2A
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• pp.137-143
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• 2011

This study evaluated the effects of maleic anhydride grafted polypropylene powder (mPP) contents on the bond properties of cement mortar and nonpolar macro synthetic fibers (macro synthetic fiber). Dog-bone bond tests were performed to evaluate the bond performance of macro synthetic fiber in cement mortar with varying amounts of mPP (0%, 5%, 10%, 15%, 20%, 25%, 30% of cement weight). The bond properties (pullout behavior, pullout load and interface toughness) of macro synthetic fiber in cement mortar increased as the mPP contents was increased. The bond properties increased with the mPP contents. The microstructure of macro synthetic fiber surface was examined after the pullout test to analyze the frictional resistant force according to mPP contents during the pullout process of macro synthetic fiber in cement mortar. The scratched of macro synthetic fiber increased with the mPP contents.