• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.102-108
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• 2010

The main objective of this study was to evaluate the effect of recycled PET (RPET) fiber made from waste PET bottles to examine application on concrete member. To evaluate the reinforcement effect of RPET fiber in concrete member, experimental tests were performed, such as mechanical property tests (compressive strength, modulus of elasticity and splitting tensile strength) and drying shrinkage test. In mechanical property tests, compressive strength and modulus of elasticity in concrete mixed with RPET fiber gradually decreased, but splitting tensile strength gradually increased as volume fraction of fiber increased. In drying shrinkage test, free drying shrinkage increased. In restrained case, in contrast, crack occurrence was delayed because of tensile resistance increase by RPET fiber. The comparison of RPET and PP fiber added concrete specimen's properties showed that two materials had similar properties. In conclusion, RPET fiber is an alternative material of PP fiber, even finer for its excellence in eco-friendliness due to the recycling of waste PET bottles and its possible contribution to the pollution declination.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.1
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• pp.114-123
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• 2013

This study was performed to verify the structural reinforcing effect of recycled polyethylene terephthalate (PET) fiber. In order to verify the structural reinforcing capacity of RPET fiber, recycled PET fiber added RC slab specimens were prepared to examine the flexural capacity while those of plain concrete and those of added with PP fiber, and the behavior of the specimens were also evaluated. The result shows that the compressive strength reduces as the fiber volume fraction increases, and the rate of reduction varies from 2% to 7%. The result of the flexural capacity shows that the ultimate capacity of plain specimens is the highest compare to those fiber reinforced specimens, but it has shown that specimens reinforced by 5% PET fiber has the highest energy absorption and the ductility index. In the application of PET fiber in slab specimens has shown that ductility capacity have increased where the ultimate capacity decreasing. That is the different tendency of beam specimens, which the ultimate capacity and the ductility of those have both shown the improvement compare to plain concrete specimens, which means the reinforcing effect of PET fiber in slab is less strong than in beam. Therefore, the application of PET fiber in slab structures as reinforcement needs the proper mix proportion of concrete and volume fraction of PET fiber with deep consideration of the structures.

• Journal of the Society of Disaster Information
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• v.13 no.2
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• pp.213-220
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• 2017

Organic fiber reinforced concrete is applicable to many applications for construction material. In general, organic fibers have low tensile strength and elastic modulus, but they have many advantages such as high crack resistance, impact resistance, chemical resistance, flexural behavior and corrosion resistance. In this study, hybrid organic fibers were prepared by mixing polyamide (PA) fibers and high strength polyester (PET) fibers. Then, flexural performance test of fiber reinforced concrete containing hybrid organic fiber was performed. The energy absorption capacity of the hybrid organic fiber reinforced concrete was evaluated.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.305-306
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• 2009

This study is on basic experimental methods of easily verifying the fiber content in non-spalling concrete at construction sites. As a result, fiber content in a mixture can be effectively measured by using 15$\ell$ of water for dilution of specimens, dry bit trowel for tool, and microwave for drying.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.461-464
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• 2008

This study is compactability and Passing ability to get to know the flowing characteristic of high flowing self-compacting concrete with mixing steel fiber of various size and diameter. After flowing test, size and diameter are getting longer, flowing performance is getting lower. It meets the standard of combined high flowing self-compacting concrete of JSCE 2 grade and passing performance from ASTM C 1621. Through this study, it can be possible to be applied in site of HSCC with mixing steel fiber.

• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.759-766
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• 2004

The addition of steel fiber with concrete significantly improves the engineering properties of structural members, notably shear strength. The purpose of this study is to determine the steel fiber shape, aspect ratio and volume fraction ratio in a point of practical usage as structural members. Steel fiber factor and volume fraction are also considered to verify the strengthening effect in member level. From the reviewing of previous researches and analyzing of consecutive material test results, the optimum shape and length of steel fiber, which can have a good strengthening effects were defined as a hooked end type and larger than 1.5 times of maximum gravel size. Analyzing the test results of strength and deformation capacity, aspect ratio 75 and volume fraction $1.5\%$ can be having a maximum strengthening effect of steel fiber. Also steel fiber factor, tensile splitting strength, and flexural strength are found as key parameter in shear strengthening effect in member level.

• Resources Recycling
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• v.24 no.4
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• pp.3-11
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• 2015

The negative effects of unburned fabric in municipal solid waste incinerator (MSWI) ash on the performances of cement composite were investigated. The chemical and physical characteristics of MSWI ash powder containing high volume of unburned fabric were analyzed. The workability and compressive strength of mortar-type cement composites with the ash powder were evaluated. The workability of the cement composites was decreased mainly by unburned fabric in the ash, while the compressive strength was decreased by MSWI ash itself. From the experimental results, the critical limits for both MSWI ash and their powder containing unburned fabric in the cement composites should be limited from standpoint of the workability of the composite.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.189-196
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• 2018

Degraded shear performance of reinforced concrete members with recycled coarse aggregate (RCA) compared to flexural strength is a problem. To address this, steel fibers can be used as concrete reinforcement material. In this study, the strength and deformation characteristics of SFRC beams using RCA were to be determined by shear tests. Major experimental variables include the volume fraction of steel fiber (0, 0.5%, 1%), the replacement rate of RCA (0%, 100%), and the shear span ratio (a/d = 1, 2). As a result of the experiment, the shear strength of the specimen increased as the rate of mixing steel fiber increased. For specimens with RCA and 1% steel fiber, the maximum shear strengths increased by 1.77 - 6.25% compared to specimens with normal coarse aggregate (NCA). On the other hand, at 0-0.5% steel fiber, the shear strengths of RCA specimens were reduced by 24.2% to 49.2% compared to NCA specimens. This indicates that reinforcement with 1% volume fraction of steel fiber greatly contributes to preventing shear strength reduction due to the use of RCA.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.59-60
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• 2009

Steel fibers are recently well recognized for good composite/strengthening materials because of their ductile behavior and good performance on crack control and shear behavior compared to concrete materials. Especially, the great improvement in shear strength by steel fibers led researchers to be involved in many experimental studies. However, our understanding on the complex shear behavior of the steel fiber reinforced concrete(SFRC) members are still very limited, and the fundamental test data are also not enough. In this study, therefore, 4 SFRC specimens were fabricated and tested, from which the effectiveness of steel fibers as shear reinforcement were evaluated. The test results shows that the shear strength of SFRC members increases as the amount of steel fibers increases.

• Composites Research
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• v.23 no.4
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• pp.35-43
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• 2010

The purpose of this paper is to develop a Hybrid Fiber-reinforced High Strength Lightweight Cementitious Composite (HFSLCC) incorporated with lightweight filler and hybrid fibers for lightness and high ductility. Optimal ingredients and mixture proportion were determined on the basis of the micromechanical analysis and the steady-state cracking theory considering the fracture characteristics of matrix and the interfacial properties between fibers and matrix. Then 4 mixture proportions were determined according to the type and amount of fibers and the experiment was performed to evaluate the mechanical performance of those. The HFSLCC showed 3% of tensile strain, 4.2MPa of ultimate tensile stress, 57MPa of compressive strength and $1,660kg/m^3$ of bulk density. The mechanical performance of HFSLCC incorporated with PVA fibers of 1.0 Vol.% and PE fibers of 0.5 Vol.% is similar to those of the HFSLCC incorporated with fibers of 2.0 Vol.%.