• 대한토목학회논문집
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• 제26권6A호
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• pp.1033-1039
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• 2006

본 연구의 목적은 1.8 mm의 높이와 6 mm의 주기를 가지고 있는 crimped type 합성섬유로 보강된 시멘트 복합재료의 부착 및 휨특성과 소성수축균열제어 특성을 평가하는 것이다. 부착 및 휨 시험은 JCI SF-4 및 JCI SF-8에 의해서 실시하였고, 소성수축균열시험은 시멘트 복합재료의 소성수축균열의 감소에 영향을 미치는 섬유의 효과를 평가하기 위하여 실시하였다. 실험결과 crimped type 합성섬유는 직선형태의 섬유와 비교하여 부착하중 및 계면인성이 우수하였고, 콘크리트의 휨인성을 증가시켰다. 또한 crimped type 합성섬유는 섬유의 혼입율이 0.00%에서 1.00%로 증가함에 따라 소성수축균열 저항성이 증가하였다. 특히, 섬유의 혼입율이 0.50% 이상이 되면 소성수축균열 조절능력이 매우 우수하였다.

• 콘크리트학회논문집
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• 제14권4호
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• pp.474-482
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• 2002

본 연구의 목적은 섬유의 부착시험을 통하여 섬유의 파괴없이 최대 인발저항을 가지고 시멘트 모체 내에서 완전한 정착작용을하는 구조용 합성섬유의 최적형상과 최적형상함수를 도출하는데 있다. 7가지 다른 형상의 구조용 합성섬유를 조사하였고 부착시험을 수행하였다. 부착시험의 변수는 7가지의 다른 형상이고, 2종류의 시멘트 모르타르의 배합이다. 부착시험 결과, 7가지 다른 형상중 crimped type이 계면인성(인발에너지)와 인발하중에서 가장 우수한 성능을 보였다. Crimped type을 기본으로 하여 섬유의 주기와 높이를 바꾸어 부착시험을 실시한 결과 최적형상함수, D= $b^{{\alpha}ο{\alpha}}$ $h^{λ{\beta}}$ 를 도출하였다.

• 한국염색가공학회지
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• 제33권4호
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• pp.182-190
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• 2021

The purpose of this study is to provide the dyeing and physical characteristics of napped knit fabrics composed of latent crimped yarn. The K/S values, dyeing fastness, thickness, bulkiness, and shrinkage characteristics of three knit fabrics were investigated. The original knit fabric (SK) was composed of 1ply latent crimped yarn (75/36) in the ground and PET DTY (70/100) in the pile loop, in order of napped process the napped knit fabric (SN) was napped SK fabric. In order to compare of latent crimped yarn content, the last knit fabric (DN) was napped 2ply latent crimped yarn were included in the same structure of SK. Dyeability of three knit fabrics was similar but the shrinkage properties of DN fabric were significant different. The bulkiness shows a tendency to increase the bulkiness as increasing the dyeing temperature, and the bulkiness of the SN was higher because of the napping process and optimal content of latent crimped yarn.

• 산업기술연구
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• 제19권
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• pp.163-172
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• 1999

This study is conducted on the flexural toughness and flexural fatigue test to fine the mechanical properties of steel fiber reinforced rapid-set cement concrete. Experimental investigation is examined according to fiber contents(0, 0.4, 0.7, 1.0, 1.5%), fiber aspect ratio(58, 60, 83), fiber type (hooked, crimped fiber), and cement type (normal portland & rapid-set cement). The principal results obtained through this study are as follows; toughness and fatigue resistance tend to considerably increase with fiber contents, fiber aspect ration. And hooked fiber is improved better than crimped fiber. Concrete using rapid set cement is increased strength properties compared with concrete using normal portland cement, but relative strength properties behavior and fatigue resistance show a tendency to decrease a little.

• Computers and Concrete
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• 제26권5호
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• pp.451-465
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• 2020

This paper presents experimental and numerical investigations on mechanical properties of ultra-high-performance fiber-reinforced concrete (UHPFRC) with four types of steel fibers; micro steel (MS), crimped (C), round crimped (RC) and hooked-end (H), in two fiber contents of 1% and 2% (by volume) and two lengths of 13 and 30 mm. Compression, direct tension, and four-point bending tests were carried out on four types of specimens (prism, cube, dog-bone and cylinder), to study tensile and flexural strength, fracture energy and modulus of elasticity. Results were compared with UHPC specimens without fibers, as well as with available equations for the modulus of elasticity. Specimens with MS fibers had the best performance for all mechanical properties. Among macro fibers, RC had better overall performance than H and C fibers. Increased fibers improved all mechanical properties of UHPFRC, except for modulus of elasticity, which saw a negligible effect (mostly less than 10%). Moreover, nonlinear finite element simulations successfully captured flexural response of UHPFRC prisms. Finally, nonlinear regression models provided reasonably well predictions of flexural load-deflection behavior of tested specimens (coefficient of correlation, R² over 0.90).

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2000년도 봄 한국섬유공학회 학술발표회 논문집(Proceedings of the Korean Textile Conference)
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• pp.279-282
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• 2000

• Advances in concrete construction
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• 제12권6호
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• pp.499-505
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• 2021

Geopolymer binders fascinate the attention of researchers as a replacement to cement binder in conventional concrete. One-ton production of cement releases one ton of carbon-dioxide in the atmosphere. In the replacement of cement by geopolymer material, there are two advantages: one is the reduction of CO₂ in the atmosphere, second is the utilization of Fly ash and Ground granulated blast furnace slag (GGBFS) are by-products from coal and steel industries. This paper focuses on the mechanical properties of steel fiber reinforced geopolymer concrete. The framework considered in this research work is geopolymer source (Fly ash, GGBFS and crimped steel fibre) and alkaline activator which consists of NaOH and Na₂SiO₃ of molarity 8M. Here the Na₂SiO₃ / NaOH ratio was taken as 2.5. The variables considered in this experimental work include Binder content (360,420 and 450 kg/m³), the proportion of Fly ash and GGBS (70-30, 60-40 and 50-50) for three different grades of Geopolymer concrete (GPC) GPC 20, GPC 40 and GPC 60. The percentage of crimped steel fibres was varied as 0.1%, 0.2%, 0.3%, 0.4% and 0.5%. Generally, the inclusion of steel fibres increases the flexural and split tensile strength of Geopolymer concrete. The optimum dosage of steel fibres was found to be 0.4% (by volume fraction).

• Smart Structures and Systems
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• 제24권2호
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• pp.157-171
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• 2019

This study investigated the effects of the geometric parameters of superelastic shape memory alloy (SE SMA) fibers on the pullout displacement recovering and self-healing capacity of reinforced cementitious composites. Three diameters of 0.5, 0.7 and 1.0 mm and two different crimped lengths of 5.0 and 10.0 mm were considered. To provide best anchoring action and high bond between fiber and cement mortar, the fibers were crimped at the end to create spear-head shape. The single fiber cement-based specimens were manufactured with the cement mortar of a compressive strength of 84 MPa with the square shape at the top and a dog-bone shape at the bottom. The embedded length of each fiber was 15 mm. The pullout test was performed with displacement control to obtain monotonic or hysteretic behaviors. The results showed that pullout displacements were recovered after fibers slipped and stuck in the specimen. The specimens with fiber of larger diameter showed better displacement recovering capacity. The flag-shaped behavior was observed for all specimens, and those with fiber of 1.0 mm diameter showed the clearest one. It was observed that the length of fiber anchorage did not have a significant effect on the displacement recovery, pullout resistance and self-healing capacity.

• 한국염색가공학회지
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• 제30권2호
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• pp.70-76
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• 2018

The dyeing behaviors of poly(ethylene terephthalate)(PET) bulky yarns, DTY(draw textured yarn) and SSY(latent crimped yarn), were investigated with different energy type disperse dyes compared with those of SDY(spin draw yarn). The maximum exhaustions of E-type disperse Red 60, Blue 56 and Yellow 54 on SSY were 99%, 94% and 93%, respectively. The maximum exhaustions of S-type disperse Red 179, Blue 79 and Orange 30 on SSY were 96%, 97% and 97%, respectively. The K/S values of SSY were significantly higher than those of DTY and SDY in all energy type of disperse dyes. The knit fabric composed of SSY became bulky at the end of high temperature dyeing process because of their thermal shrinkage property due to melt viscosity difference.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.335-340
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• 2001

Recently in abroad, structural synthetic fiber developed, has been studied extensively as a substitute for steel fiber due to its properties such as corrosion-resistance, low density, good pumping, and in-place safety, etc. In this study, we conducted pull-out test, for seven different geometries of structural synthetic fibers and obtained optimum geometry for structural synthetic fiber which fully utilizes matrix anchoring without revealing fiber fracturing. According to pull-out test results, it was found that crimped type structural synthetic fiber give significant improvement in the interface toughness(roll-out enemy) and pull-out load.