• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.104.2-104.2
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• 2007

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.353-358
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• 2001

The cement concrete pavements are designed twenty years of performance life in Korea. At the present time, some expressways have been elapsed seventy percent of performance life which are detecting local failures. The most repair methods using to repair failures are partial depth repair and full section repair. These methods are most important bonding strength between rapid curing materials and substrate concrete pavements. This study was performed to evaluate bonding strength of the composites section made of rapid curing material and substrate concrete pavements. The pull-out tester was used to test bonding strength for the composites section made of each materials. In the results of the test, the bonding strength values of the epoxy mortar and acrylic mortar are higher than those of the other materials. The performance life of repaired section is affected by various factor. The bonding strength of bonded composites section may be affect the performance life, significantly.

• Journal of the Korea Concrete Institute
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• v.16 no.2 s.80
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• pp.175-184
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• 2004

When the columns of existing RC structures are repaired with FRP composites, the core concrete of the columns is confined by both materials of steel spirals (or steel hoops) and FRP composites because the FRP composites wrap the existing columns which have been already confined with steel spirals or hoops. As the stress-strain curves of steel and fiber are different to each other, the behavior of concrete columns confined with both steel spiral and FRP composites is also different to that of concrete columns confined with only steel spiral or FRP composites. Twenty four RC cylinders were tested in order to observe the behavior of RC cylinders confined with both materials. The observed results of the test showed that the behavior of the test cylinders confined with both materials was quite different to that of cylinders confined with only one material.

• Steel and Composite Structures
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• v.4 no.5
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• pp.333-353
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• 2004

Strength of reinforced concrete beams can easily be increased by the use of externally bonded CFRP composites. However, the mode of failure of CFRP strengthened beam is usually brittle due to tension-shear failure in the concrete substrate or bond failure near the CFRP-Concrete interface. In order to improve the ductility of CFRP strengthened concrete beams, critical variables need to be investigated. This experimental and analytical research focused on a series of reinforced concrete beams strengthened with CFRP composites to enhance the flexural capacity and ductility. The main variables were the amount of CFRP composites, the amount of longitudinal and shear reinforcement, and the effect of CFRP end diagonal anchorage system. Sixteen full-scale beams were investigated. A new design guideline was proposed according to the effects of the above-mentioned variables. The experimental and analytical results were found to be in good agreement.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.313-316
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• 2004

In this paper, it was assessed durability of ultra-high strength cementitious composites(UHSCC) with the range of 180MPa of compressive strength through the test method of chloride ion resistance, carbonation, freezing-thawing resistance, permeability. In order to compare with ultra-high strength cementitious composites, normal concrete and high-strength concrete were also tested. As the experimental result, it showed that UHSCC was cleary superior to the durability performance of normal concrete and high-strength concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1991.10a
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• pp.99-106
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• 1991

Result of an experimental study on the manufacture, the mechanical properties and waterightness 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 plysical properties such as compresive, tensile and flectural strengths, watertightness and cement composites are improved by using a small amount of stylene butadiene rubber latex.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.144-149
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• 1993

The results of an experimental study on the manufacture and the mechanical properties of carbon fiber reinforced silica fume.cement composites and light weight fly ash.cement composites are presented in this paper. The CF reinforced silica fume.cement composites using silica fume early strength cement were prepared with Pan-derived or Pitch-derived CF, and Lt. Wt, fly ash.cement composites using fly ash, early strength cement, perlite and a small amount of foaming agent. As the test results show, the flexural strength, toughness and ductility of CF reinforced silica fume .cement composites were remarkably increased by fiber contents. Also, the manufacturing process technology of Lt. Wt. fly ash.cement composites was developed and its optimum mix proportions were proposed. And the compressive and flexural strength of the fly ash.cement composites by hot water cured were improved even more than by moist cured, but are decreased by increasing fly ash replaced ratio for cement.

• Composites Research
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• v.37 no.3
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• pp.226-231
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• 2024

Coal ash has been used as a sand replacement in the construction industry. Due to the use of bituminous coal as a result of anthracite depletion, and quicklime as an air purifier in the desulfurization process, pop-out defects have recently occurred in concrete using coal ash, severely limiting the recycling of coal ash into concrete. In this study, the components that cause the pop-out problem of the coal ash filled concrete were identified and a pretreatment method to fully expand the expansive components in advance was proposed as a solution to this problem. By treating water twice for 10 min, allowing the CaO mixed in the coal ash to fully expand, the problems of pop-out and reduced compressive strength of the concrete were overcome. The cost and time efficient water treatment method proposed in this study is expected to promote the recycling of coal ash into concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.165-168
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• 2005

Carbon Fiber Reinforced Polymer(CFRP) composites are widely applied to strengthen deteriorated concrete structures. This paper presents the experimental results of the performance of reinforced concrete(RC) decks strengthened with CFRP composites. Simple span decks with 2m span length were tested to investigate the effect of CFRP reinforcement types on the flexural behavior of strengthened RC beams. The test results were analyzed with the special emphasis on the failure mode and the maximum load.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.429-434
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• 2005

In this paper sandwich structures like beams and plates are optimised by using parametric study. The structures are composed of fibre reinforced composites for facial material and resin concrete and PVC foam for core materials. The stacking sequences and thickness of the composites are controlled as major parameters to find out the optimal condition for machine tool components. For the plate structure for machine tool bed composites-skined sandwich structure which has several ribs are proposed to enhance both directional bending stiffnesses at the same time. From the results optimal configuration and materials for high precesion machine tools are proposed.