• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.391-401
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• 2017

In this study, the effects of water-to-binder (W/B) ratio and replacement ratio of blast furnace slag (BFS) on the compressive strength of concrete were first investigated to determine an optimized mixture. Then, using the optimized high-strength concrete (HSC) mixture, hooked steel fibers with various aspect ratios and volume fractions were used as additives and the resulting mechanical properties under compression and flexure were evaluated. Test results indicated that replacement ratios of BFS from 50 to 60% were optimal in maximizing the compressive strength of steam-cured HSCs with various W/B ratios. The use of hooked steel fibers with the aspect ratio of 80 led to better mechanical performance under both compression and flexure than those with the aspect ratio of 65. By increasing the fiber aspect ratio from 65 to 80, the hooked steel fiber volume content could be reduced by 0.25% without any significant deterioration of energy absorption capacity. Lastly, complete material models of steel-fiber-reinforced HSCs were proposed for structural design from Lee's model and the RILEM TC 162-TDF recommendations.

• Polymer(Korea)
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• v.31 no.4
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• pp.349-355
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• 2007

Poly(N-isopropylacrylamide-co-acrylonitrile) [P(NIPAAm-co-AN)] copolymers with AN content of up to 10 mol% and their hydrogels were synthesized using water as a reaction medium, and the effects of AN unit incorporation on the critical gel transition temperature(CGTT) and swelling behaviors of the hydrogels were investigated. The CGTT of the copolymer hydrogel was $30{\sim}32\;^{\circ}C$, decreasing with increasing AN content. Below CGTT, swelling rate and equilibrium swelling ratio of the copolymer hydrogel decreased with increasing AN content. On the other hand, it exhibited faster deswelling and lower equilibrium deswelling ratio with increasing AN content above CGTT.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.749-752
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• 2008

The effects of fiber content on strength properties of ultrarapid-hardening polymer-modified concretes with fiber. As a result, the compressive and flexural strengths of ultrarapid-hardening polymer-modified concretes with fiber increase with increasing of fiber content. In particular, the ultrarapid-hardening polymer-modified concretes with a polymer-cement ratio of 20% and a fiber content of 0.08% provide approximately two times higher flexural strength than unmodified concretes. Such high strength development is attributed to the high tensile strength of polymer and fiber and the improved bond between cement hydrates and aggregates because of the addition of polymer and fiber.

• Geomechanics and Engineering
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• v.2 no.1
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• pp.19-28
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• 2010

This paper describes the compaction and strength behavior of black cotton soil (BC soil) reinforced with coir fibers. Coir used in this study is processed fiber from the husk of coconuts. BC soil reinforced with coir fiber shows only marginal increase in the strength of soil, inhibiting its use for ground improvement. In order to further increase the strength of the soil-coir fiber combination, optimum percentage of 4% of lime is added. The effect of aspect ratio, percentage fiber on the behavior of the composite soil specimen with curing is isolated and studied. It is found that strength properties of optimum combination of BC soil-lime specimens reinforced with coir fibers is appreciably better than untreated BC soil or BC soil alone with coir fiber. Lime treatment in BC soil improves strength but it imparts brittleness in soil specimen. BC soil treated with 4% lime and reinforced with coir fiber shows ductility behavior before and after failure. An optimum fiber content of 1% (by weight) with aspect ratio of 20 for fiber was recommended for strengthening BC soil.

• Food Science of Animal Resources
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• v.37 no.6
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• pp.948-954
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• 2017

The objective of this study was to investigate the relationship between muscle fiber characteristics and fatty acid composition of four major muscles in Korean native black goat (KNBG). Longissimus lumborum (LL), psoas major (PM), semimembranosus (SM), and gluteus medius (GM) were obtained from five male KNBGs of 36 mon of age and subjected to histochemical analysis and to determine fatty acid composition and meat quality traits. There were significant (p<0.05) differences in fiber number percentage (FNP) and fiber area percentage (FAP) of fiber types among these four muscles. PM had the highest FNP of type I and the lowest FNP of type IIB, while SM had the highest FNP of type IIB. The highest fat content was observed in LL while SM had the lowest fat content. The proportions of SFA and MUFA were significantly (p<0.05) different among four muscles due to differences in the majority of fatty acids such as oleic (C18:1) and palmitic (C16:0) acids. The PUFA/SFA ratio was significantly (p<0.05) different among four muscles, and the highest PUFA/SFA ratio was observed in PM. Results suggested that LL and PM might be healthful because of higher desirable fatty acid value and PUFA/SFA ratio, respectively. Also, data showed that correlations between muscle fiber types and fatty acids proportion of goat muscles were reversed with those of cattle muscles.

• Journal of the Korean GEO-environmental Society
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• v.13 no.8
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• pp.45-55
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• 2012

This study is about the application of waste stone sludge as fill material. Waste stone sludge, weathered granite soil, and the mixture of the former and the latter strengthened with staple fiber are experimentally analyzed for measuring strength property. When staple fiber was mixed with waste stone sludge, weathered granite soil, and the mixture, there was a nearly linear relationship between the amount of the staple fiber and the increasing ratio of unconfined compressive strength. The increasing ratio of unconfined compressive strength was the largest in weathered granite soil. The increasing ratio of unconfined compressive strength of the mixture was similar to that of waste stone sludge. In the case of the mixture of weathered granite soil and waste stone sludge, an internal friction angle tended to increases rely on increasement of staple fiber content, whereas the change of cohesion was small. An internal friction angle was increased by 21 percent when staple fiber content is 0.75 percent. Comparing with weathered granite soil or waste stone sludge, strength parameters of the mixture were increased relatively. Thus strengthening effect of staple fiber in the mixture is expected.

• International Journal of Safety
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• v.11 no.2
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• pp.26-28
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• 2012

In this thesis, fracture tests were carried out in order to investigate the flexural strength behavior of FRC(fiber reinforced concrete) structures. FRC beams were used in the tests, the initial crack load and the ultimate load of the beams were observed under the static loading. According to the results, the ultimate loads increase with the fiber content, and these tendency is clear in the specimens with large fiber aspect ratio. From the results of the regression analysis, practical formulae for predicting the flexural strength of FRC were suggested.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.293-298
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• 1998

The result of an experimental study on the mechanical properties and durability of polypropylene fiber reinforced concrete are presented in this paper. This study has been performed to obtain the properties of PFRC such as strength, toughness and durability. The test variables are fiber content, fiber types, W/C ratio. PFRC shows the highest strength when the polypropylene fiber contents were increased to 2.0 vol.%. Also, freeze-thaw resistance and carbonation were somewhat more improved than plain concrete.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.4
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• pp.73-81
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• 2010

The cemented sand and gravel (CSG) method is a construction technique that adds cement and water to rock-like materials, such as rivered gravel or excavation muck which can be obtained easily at areas adjacent to dam sites. This study was performed to evaluate the compaction and compressive strength properties of stress-strain, elastic modulus and fracture mode CSG materials reinforced polypropylene fiber. Polypropylene fiber widely used for concrete reinforcement is randomly distributed into cemented sand. The two types of polypropylene fiber (monofillament and fibrillated fiber) were used and fiber fraction ratio was 0, 0.2 %, 0.4 %, 0.6 % and 0.8 % by the weight of total dry soil. The effect of fiber fraction ratio and fiber shape on compaction and compressive strength were investigated. The optimum moisture contents (OMC) of CSG material increased as fiber fraction increased and the dry density of CSG material decreased as fiber fraction. Also, the maximum increase in compressive strength was obtained at 0.4 % content of monofillament and fibrillated fiber. CSG material behaviour was controlled not only by fiber fraction but also fiber distribution, fiber shape and fiber type.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.39-42
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• 2005

This study investigates influence of organic fiber reinforced materials, affecting crack reduction of cement mortar using low grade natural sand(LNS). According to the test, for the properties of fresh mortar, the mortar using natural sand(NS) exhibited that flow value increased until adding most of fiber less than 1$\%$, except for Polyvinly alchol fiber(PVA), and then it decreased. Meanwhile, the mortar mixed with LNS showed that increase of fiber content decrease flow value, regardless of fiber type. Air content increased in the mortar adding nylon fiber(NY) and polypropylene fiber(PP), while it maintained or decreased in the mortar adding cellulose fiber(CL) and PVA. Compressive strength of the mortar does not affect during early age, but mortar using NS and adding 0.1$\%$ of fiber content increased the value, except for PP, at 28 age days, while the mortar mixed with LNS decreased. For the properties of tensile strength, mortar, using NS and adding individually PP and PVA, exhibited higher value. Especially 0.1$\%$ of NY provided the highest value. In addition, the mortar mixed with LNS resulted in improved tensile value as fiber content increased. It is demonstrated that mortar using LNS led to higher length change ratio than natural sand.