• Journal of the Korean Society of Clothing and Textiles
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• v.35 no.8
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• pp.1006-1013
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• 2011

An enzymatic treatment method using alcalase was introduced to improve the moisture characteristic of the polyamide fiber. The alcalase treatment conditions such as the pH, treatment temperature, enzyme concentration, and treatment time were optimized by measuring the amino groups. The changes in the weight loss, tensile strength, moisture regain, water contact angle (WCA), and water absorption rate of the polyamide fiber with the changes in the alcalase treatment conditions were evaluated. The optimum alcalase treatment conditions for polyamide fiber were found to be a treatment temperature of 50oC, a treatment time of 50 minutes, an alcalase concentration of 10% (owf), and a pH of 7.0. The ethylenediaminetetraacetic acid (EDTA) and L-cysteine accelerated the activity of the enzyme; however, they did not have an effect on the amino group production of the fiber surface. The alcalase treatment of the polyamide fiber improved the fiber's moisture regain, WCA, and absorption rate due to the amino group on the fiber surface. The results showed that the alcalase treatment of polyamide fiber is an effective method to improve the moisture characteristic of the polyamide fiber.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.73-74
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• 2018

In this study, it evaluate the tensile properties of polyamide fiber reinforced cementitious composite and hooked steel fiber reinforced cementitious Composites by strain rate. Polyamide fiber reinforced cement composites (PAFRCC) and Hooked Steel Fiber Reinforced Cement Composite(HSFRCC) were fabricated. Each specimen was reinforced with 1.0 and 2.0vol% fiber. The length of the reinforced fiber was 30 mm for both fibers, and the tensile test specimen was made in dumbbell shape. As a result, the tensile strength of fiber in polyamide fiber and the mechanical bonding between fiber and matrix in hooked steel fiber are considered to be the main factors affecting tensile behavior of fiber reinforced cement composite.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.2
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• pp.78-83
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• 2012

Steel fiber reinforced shotcrete in tunneling construction has some problems in terms of constructability, durability and lots of rebound wastage. In order to resolve these problems, this pater proposes polyamide fiber reinforced shotcrete technology. And this paper presents the results of experimental construction of the polyamide fiber reinforced shotcrete technology. The results of the study are as follows. 1. The polyamide fiber reinforced shotcrete suggested in this paper shows outstanding mechanical performance that meets various Korean tunnel construction design criteria. 2. In addition, the results of experimental constructions show that the polyamide fiber reinforced shotcrete creates less rebound and wasted product than the steel fiber reinforced shotcrete. Based on the above results, it is concluded that the polyamide fiber reinforced shotcrete technology can be used as economical and environmentally friendly construction of tunnel.

• Nuclear Engineering and Technology
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• v.47 no.7
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• pp.884-894
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• 2015

Background: Fibers in concrete resist the growth of cracks and enhance the postcracking behavior of structures. The addition of fibers into a conventional reinforced concrete can improve the structural and functional performance of safety-related concrete structures in nuclear power plants. Methods: The influence of fibers on the ultimate internal pressure capacity of a prestressed concrete containment vessel (PCCV) was investigated through a comparison of the ultimate pressure capacities between conventional and fiber-reinforced PCCVs. Steel and polyamide fibers were used. The tension behaviors of conventional concrete and fiber-reinforced concrete specimens were investigated through uniaxial tension tests and their tension-stiffening models were obtained. Results: For a PCCV reinforced with 1% volume hooked-end steel fiber, the ultimate pressure capacity increased by approximately 12% in comparison with that for a conventional PCCV. For a PCCV reinforced with 1.5% volume polyamide fiber, an increase of approximately 3% was estimated for the ultimate pressure capacity. Conclusion: The ultimate pressure capacity can be greatly improved by introducing steel and polyamide fibers in a conventional reinforced concrete. Steel fibers are more effective at enhancing the containment performance of a PCCV than polyamide fibers. The fiber reinforcementwas shown to bemore effective at a high pressure loading and a lowprestress level.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.470-476
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• 2016

Many studies have been performed on hybrid fiber reinforced concrete for years, which is to improve some of the weak material properties of concrete. Studies on characteristics of hybrid fiber reinforced concrete using amorphous steel fiber and polyamide fiber, however, yet remain to be done. The purpose of this experimental research is to evaluate the workability and mechanical properties of hybrid fiber reinforced concrete using amorphous steel fiber and polyamide fiber. For this purpose, the hybrid fiber reinforced concrete containing amorphous steel fiber(ASF) and polyamide fiber(PAF) were made according to their total volume fraction of 0.5 % for water-binder ratio of 33 %, and then the mechanical properties such as the compressive strength, direct tensile strength, flexural strength, and flexural toughness of those were estimated. It was observed from the test results that the compressive strength was slightly decreased with increasing ASF and decreasing PAF and the effect of fiber combination on the flexural strength was not much but the flexural toughness was relatively largely increased with decreasing ASF and increasing PAF.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.756-765
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• 2015

Background: Fibers have been used in cement mixture to improve its toughness, ductility, and tensile strength, and to enhance the cracking and deformation characteristics of concrete structural members. The addition of fibers into conventional reinforced concrete can enhance the structural and functional performances of safety-related concrete structures in nuclear power plants. Methods: The effects of steel and polyamide fibers on the shear resisting capacity of a prestressed concrete containment vessel (PCCV) were investigated in this study. For a comparative evaluation between the shear performances of structural walls constructed with conventional concrete, steel fiber reinforced concrete, and polyamide fiber reinforced concrete, cyclic tests for wall specimens were conducted and hysteretic models were derived. Results: The shear resisting capacity of a PCCV constructed with fiber reinforced concrete can be improved considerably. When steel fiber reinforced concrete contains hooked steel fibers in a volume fraction of 1.0%, the maximum lateral displacement of a PCCV can be improved by > 50%, in comparison with that of a conventional PCCV. When polyamide fiber reinforced concrete contains polyamide fibers in a volume fraction of 1.5%, the maximum lateral displacement of a PCCV can be enhanced by ~40%. In particular, the energy dissipation capacity in a fiber reinforced PCCV can be enhanced by > 200%. Conclusion: The addition of fibers into conventional concrete increases the ductility and energy dissipation of wall structures significantly. Fibers can be effectively used to improve the structural performance of a PCCV subjected to strong ground motions. Steel fibers are more effective in enhancing the shear performance of a PCCV than polyamide fibers.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.76-85
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• 2017

In this study, to evaluate the mechanical properties of fiber-reinforced cement composites by strain rate, hydraulic rapid loading test system was developed. And compressive and tensile strength of the hooked steel fiber and polyamide fiber reinforced cement composite were evaluated. As a result, the compressive strength, strain capacity and elastic modulus were increased with increasing strain rate. The effect of compressive strength by type and volume fraction of fibers was not significant. The dynamic increase factor(DIF) of the compressive strength was higher than that of the CEB-FIP model code 2010 and showed a trend similar to that of ACI-349. The tensile strength and strain capacity were increased with increasing strain rate. The hooked steel fibers were drawn from the matrix. The tensile strength and strain capacity of hooked steel fiber reinforced cement composites were increased as the strain rate increased. The tensile strength and deformation capacity of the fiber reinforced cement composites were increased. And, hooked steel fibers were drawn from the matrix. On the other hand, because the bonding properties of polyamide fiber and matrix is large, polyamide fiber was cut-off with out pullout from matrix. The strain rate effect on the tensile properties of polyamide fiber reinforced cement composites was found to be strongly affected by the tensile strength of the fibers.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.41-50
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• 2014

This study evaluated the bonding property of fiber and flexural behavior of fiber reinforced concrete. Amorphous steel fiber, hooked steel fiber and polyamide fiber was used for evaluation of bonding property and flexural behavior. As a result, the hooked steel fiber was pulled out from matrix when peak stress. However amorphous steel fiber occurred shear failure because bonding strength between fiber and matrix was higher than tensile strength of fiber. Polyamide fibers occurred significantly displacement to peak stress because of elongation of fiber. After that peak stress, fiber was cut off. Amorphous steel fiber reinforced concrete had a greater maximum flexural load compared with hooked steel fiber reinforced concrete because bonding performance between fiber and matrix was high and mixed population of fiber was many. However flexural stress was rapidly reduced in load-deflection curve because of shear failure of fiber. Flexural stress of hooked steel fiber reinforced concrete was slowly reduced because fiber was pulled out from the matrix. In the case of polyamide fiber reinforced concrete, flexural stress was rapidly lowered because of elongation of fiber. However flexural stress was increased again because of bonding property between polyamide fiber and matrix. The pull-out properties of the fiber and matrix has effect on the deformation capacity and flexural strength of fiber reinforced concrete.

• Journal of the Society of Disaster Information
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• v.7 no.4
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• pp.286-293
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• 2011

Accordingly architectural structure is getting high-rise and bigger, a use of high strength and high performance concrete has been increased. High performance concrete has cons of explosion in a fire. This explosion in the fire can cause the loss of the sheath on a concrete surface, therefore it effects that increasing a rate of heat transmission between the steel bar and inner concrete. Preventing this explosion of high performance concrete in the fire, many kinds of researches are now in progressing. Typically, researches with using polypropylene-fiber and steel-fiber can prove controling the explosion, but the reduction of mobility was posed as a problem of workability. Consequently, to solve the problem as mentioned above, concrete cans secure fire resisting capacity through the using of coating liquid, including Ester-lubricant and non-ionic characteristic surfactant. This research has been drawn a ideal condition in compressive strength areas of concrete by an experiment. When applying 13mm of polyamide fiber, proper fiber mixing volume by compressive strength areas of concrete more than 2.5kg in 160MPa. These amount of a compound can control the explosion.

• Proceedings of the Korean Fiber Society Conference
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• 2001.04a
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• pp.99-102
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• 2001