• Proceedings of the Materials Research Society of Korea Conference
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• 1997.05a
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• pp.69-69
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• 1997

• Magazine of the Korea Concrete Institute
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• v.3 no.3
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• pp.101-110
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• 1991

Results of an experimental study on the manufacture, the mechanical properties and watertightness of pitch - based carbon fiber reinforced fly ash. cement composites are presented in this paper. The carbon fiber reinforced fly ash. cement composites using early strength cement silica powder and a small amount of stylene butadiene rubber latex are prepared with carbon fiber, foaming agents and mixing conditions. As a result, the mechanical and physical properties such as compressive , tensile and flexural strengths, watertightness and drying shrinkage of lightweight carbon fiber reinforced fly ash cement composites are Improved by using a samll amount of stylene butadiene rubber latex. Also, the manufacturing pnx:ess technology of carbon fiber reinforced fly ash . cement composItes is developed. The development and applications of precast products of lightweight carbon fiber remforced cement composites are expected in the near future.

• Journal of the Korean Ceramic Society
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• v.34 no.1
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• pp.56-62
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• 1997

The PAN (Polyacrylonitrile) based carbon fiber-ceramic composites (CFCC) were prepared from mixtures of short carbon fibers, phenolic resin and ceramic binder. The effects of carbonization temperature of a pre-cursor fiber, the stabilized PAN fiber, on the specific surface area and the bending strength of the activated CFCC were studied in this work. The precursor fiber was carbonized at 80$0^{\circ}C$ and 100$0^{\circ}C$, respectively. The CFCC were activated at 85$0^{\circ}C$ in carbon dioxide for 10~90 minutes. As the burn-off of the activated CFCC made of the precursor fiber carbonized at 80$0^{\circ}C$ was increased from 37% to 76%, the specific surface area in-creased from 493m2/g to 1090m2/g, and the bending strength decreased from 4.5MPa to 1.4MPa. These values were about two times larger than those of the activated CFCC of which precursor fiber was car-bonized at 100$0^{\circ}C$. The effects of carbonization temperature of a precursor fiber on the specific surface area and bending strength of the activated CCFC were explained by bonding force between carbon fiber and car-bonized phenolic resin as well as by relative shirnkage between carbon fiber and ceramic film.

• Journal of the Korean Ceramic Society
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• v.38 no.1
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• pp.52-55
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• 2001

Polyacrylonitrile(PAN)-based 탄소섬유와 epoxy resin matrix 내에 장착된 PAN-based 탄소섬유의 전기저항을 탄소섬유와 파괴될 때까지 인장강도를 증가시키며 측정하였다. 탄소섬유가 끊어져 측정 계기가 open-circuit을 나타내기 전까지 탄소섬유의 전기저항 값은 strain이 증가할수록 증가하였으며, epoxy resin은 탄소섬유의 저항값 측정에 거의 영향을 미치지 않았다. 탄소섬유의 저항값 변화는 strain에 대해 정확도 1% 이내로 예측(calibrate)할 수 있었으며 재현성 또한 우수하였다. 따라서 탄소섬유는 재료의 기계적 강도를 증가시키기 위해 사용될 수 있을 뿐만 아니라 구조재료의 파괴를 예측할 수 있는 스마트 센서로서도 사용할 수 있다는 가능성을 확인하였다.

• Magazine of the Korea Concrete Institute
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• v.6 no.5
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• pp.158-170
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• 1994

The results of an experimental study on the manufacture and the mechanical properties of carbon fiber rekforced silica fume . cement composites and light weight fly ash . cement composites are presented in this paper. 11s the test results show, the flexural strength, fracture toughness and ductility of CF reinforced silica fume . cement composites were remarkably increased by the increase of carbon fiber contents. And the workability of the fly ash . cement composites were improved, but the compressive and flexural strength and bulk specific gravity of them are decreased by increasing the ratio of fly ash to cement. And the compressive and flexural strength of the fly ash cement composites by cured under the hot water were improved than those by mositure cured. Also, the manufacturing process technology of lightweight fly ash . cement composites in replacement of general autoclaved lightweight concrete was developed and its optimum mix proportions were proposed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.182-189
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• 2010

The strengthening performance of FRPs(Fiber Reinforced Polymers) is directly affected by the environmental conditions such as freezing-thawing and moisture because FRPs are usually bonded on the concrete surface. It is, therefore, strongly required to evaluate a durability of bond between FRPs and concrete as well as FRP materials itself. The freezing-thawing resistance of FRPs is evaluated in this study with the variables of freezing-thawing conditions, types of FRP and freezing-thawing cycles. From the test results, it is found that tensile strength and pull-off strength of CFRP are not affected by the freezing-thawing. On the other hands, those of GFRP show a little degradation because of continuous water immersion during thawing process. But, cautions are needed on the bond durability between FRPs and concrete in case of continuous water supplying from adjacent to the concrete.

• Magazine of the Korea Concrete Institute
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• v.5 no.4
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• pp.145-155
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• 1993

The results of an experimental study on the manufacture and the mechanical properties of fiber reinforced fly ash$\cdot$lime$\cdot$gypsum composites are presented in this paper. 'The composites using fly ash, lime, and gypsum were prepared with various fibers (PAN-derived and Pitch-derived carbon fiber, alkali-resistance glass fiber) and a small amount of polymer emulsion-styrene butadiene rubber latex (SBR). As the test results show, the manufacturing process technology of fly ash$\cdot$lime$\cdot$gypsum composites was developed and its optimum mix proportions were successfully proposed. And the flexural strength and toughness of fiber reinforced fly ash$\cdot$lime $\cdot$gypsum composites were increased remarkably by fiber contents, but the compressive strength of the composites were influenced by the kinds fiber more than by the fiber contents. Also, the addition of a polymer emulsion to the composites decreased the bulk specific gravity, but the compressive and flexural strength, and the toughness of the composites were not influenced by it, but were considerably improved by increasing fiber contents.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.212-218
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• 2011

The effect of composite reinforcing bars on surface electrical resistivity of concrete was investigated through experimental program. The resistivity was measured by Wenner method using an equipment with 4 probe. Ordinary steel, GFRP, and CFRP reinforcing bars produced domestically were used and a specimen with no reinforcement was tested for the comparison. This investigation is motivated from the fact that measured value of resistivity of concrete is significantly affected by details of steel reinforcements, such as location, depth and direction of the internal steel reinforcement. These results could be valuable data for evaluation of corrosion degree of concrete structures reinforced or strengthened by the composite reinforcing bars.

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.10a
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• pp.28-28
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• 1997

• Proceedings of the Korean Fiber Society Conference
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• 1997.10a
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• pp.207-210
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• 1997