현장에 적용하는 콘크리트 강도가 증가함에 따라 초고성능 콘크리트의 적용 분야가 넓어지고 있다. 초고성능 콘크리 트에는 강섬유를 일반적으로 사용하고 있지만, 이를 대체하기 위해 다양한 섬유를 연구에 적용하고 있다. 대표적으로 슈퍼섬유 라고 알려진 아라미드 섬유가 있다. 본 연구에서는 초고성능 콘크리트의 특성이 구조물 보수보강 및 내진보강에 적용하기에 적 합하다고 판단하여, 슈퍼섬유 중 하나인 파라아리미드 섬유와 조합한 복합섬유를 혼입한 초고성능 콘크리트를 보-기둥 접합부에 내진보강재로 활용하여 특성을 분석하였다. 초고성능 콘크리트의 내진보강 효과를 확인하였으며 내진상세를 적용한 실험체와 유사한 거동을 확인하였다. 초고성능 콘크리트의 높은 강도로 인해 기존 콘크리트가 파괴되는 양상이 나타나 초고성능 콘크리 트의 보수보강 효과를 모두 발휘하지 못하고 있어 추가 연구를 통해 최적의 보강단면을 설정한다면 내진보강재료로 활용할 수 있을 것으로 판단된다.

The composite PAN fibers which incorporated with CNTs and Titania were prepared by mean of wet spinning. These fibers were then pre-oxidized with microwave heating in an air atmosphere. A combination of characterizations was carried out to study the impact of nanoparticles fillers on the properties of as-spun fibers and their performance during the microwave pre-oxidation. The addition of an equal amount of fillers made obvious changes in the chemical and crystalline structure, consequently improves the strength, and this could lower the capability to creep over a wide range of temperatures in the subsequent processes. FTIR and NMR analyses results of the pre-oxidized fibers exhibited clear changes in the PAN structure, where the dehydrogenation reaction and the degree of cyclization were investigated. Additional confirmation of the occurrence of cyclization reaction was achieved by XRD and thermal analysis. According to the TGA results, the pre-oxidized CNT1/ Ti-PAN fibers exhibit greater thermal stability suggesting high carbon content and good quality could result in the dependent carbon fibers.

본 연구는 초고성능 콘크리트의 성능을 보다 향상시키기 위해 현재 콘크리트 보강에 사용하는 섬유들을 조합한 복합 섬유를 제작하여 복합섬유 혼입 초고성능 콘크리트의 강도 특성을 분석하였다. 복합섬유 4종과 단일섬유 3종을 각각 혼입하여 유동성과 압축, 휨강도 실험을 진행하였다. 복합섬유와 단일섬유 혼입 시험체 모두 유동성 평가를 만족하였으며, 단일섬유가 조금 더 우수한 성능을 나타내었다. 강도 평가결과 파라아라미드 섬유와 강섬유를 조합한 복합섬유 2종이 가장 우수한 결과를 나타내었으며, 복합섬유 직경 차이에 따라 압축 및 휨강도 보강효과가 다르게 나타난 것을 확인할 수 있었다. 압축강도 감소를 최소화하며 휨강도를 증가시킨 결과를 통해, 복합섬유는 단일섬유 간의 단점을 서로 보완할 수 있을 것으로 판단되며, 본 연구를 통해 차후 콘크리트의 다양한 재료적 특성을 보강하는 복합섬유도 충분히 제작 가능할 것으로 판단된다.

PURPOSES: This study develops eco-friendly asphalt reinforcement materials applicable to bridge deck pavement. The main purpose is to ensure highly reliable quality applicable to structures and the possibility of practical application. The main target of the study is to develop materials that are environmentally friendly and capable of improving performanceMETHODS: The application of double-reinforcement fiber improves the performance of the road pavement. 1. We use recycled film for application of sheet-typed reinforcement. 2. We use preprocessing fibers to reinforce the properties of composite pavement materials.RESULTS : The developed products may produce materials that fit the purpose of achieving stability and environmental friendliness. Sheettyped reinforcements use more than 50% recycled resin. The most important type of damage to the asphalt layer is deflection (plastic deformation). These products have a very high deflection resistance of not less than 6,000 cycles/mm. In addition, all performance is excellent. Thus, it will be easier to access the field in the future.CONCLUSIONS: Fiber-reinforced asphalt pavement showed excellent performance. Sheet-typed reinforcements containing 50% recycling resin produced good performance in terms of functionality as well as environmental friendliness. Thus, enhancing the field applicability will enhance the usability of the reinforcements.

This study fabricated low thermal conductive polyacrylonitrile (PAN)-based carbon fibers containing cellulose particles while maintaining their mechanical properties. The high thermal conductivity of carbon fibers limits their application as a high temperature insulator in various systems such as an insulator for propulsion parts in aerospace or missile systems. By controlling process parameters such as the heat treatment temperature of the cellulose particles and the amount of cellulose added, the thermal and mechanical properties of the PANbased carbon fibers were investigated. The results show that it is possible to manufacture composite carbon fibers with low thermal conductivity. That is, thermal conductivities were reduced by the cellulose particles in the PAN based carbon fibers while at the same time, the tensile strength loss was minimized, and the tensile modulus increased.

Characteristics of Al-based composites with waste stainless steel short fiber, fabricated by magnetic pulsed compaction and sintering were investigated. The compacts prepared by magnetic pulsed compaction showed high relative density and homogeneous microstructure compared with that by conventional press compaction. The relative density of sintered composites at for 1 h exhibited the same value with compacts and decreased with increase in STS short fiber content. The reaction between Al and STS phase was confirmed by the microstructural analysis using EDS. The sintered composites, prepared by magnetic pulsed compaction, showed increased hardness value with increasing STS fiber content. Maximum yield strength of 100 MPa and tensile strength of 232 MPa were registered in the AI-based composite with 30 vol% STS short fiber.

The composite used in this paper was prepared by hot-pressing ball-milled Mg alloy powders, in which NiTi shape memory alloy fibers in a row were sandwiched. The microstructure and property were examined. It is shown that the composite consisted of a homogenous matrix with uniformly distributed NiTi shape memory alloy fibers, recrystallization took place in the Mg alloy matrix which was subjected to plastic deformation an adequate bonding formed between the matrix and fibers; the density and tensile strength of the composite increased after the hot-forging; the hot-forging process is capable of improving properties of the composite.

섬유보강 시멘트계 복합재료 (이하 FRCC)는 균열 폭의 제어 등의 역학적인 효과뿐 아니라 철근방식에도 효과가 있는 것이 기존의 문헌으로부터 확인되고 있다. 본 연구에서는 아연섬유를 포함한 각종 금속섬유를 이용하여 철근의 방식효과를 부식 촉진 실험에 의해 검토했다. 더욱이 방식효과에 큰 영향을 미치는 염분침투, 희생양극 효과, 전기회로 형성에 주목하여, 각각의 요인에 있어서 검토를 실시했다. 그 결과, 금속섬유를 혼입한 FRCC의 방식효과를 확인할 수 있었으며, 특히 희생 양극효과가 높은 아연섬유의 경우, 염분침투 억제 효과가 뛰어나 내부식 성능이 향상되는 것을 확인할 수 있었다.

The purpose of study is to investigate properties of high strength concrete in fire. Composite fibers that are mixed in concrete are used to improve vulnerable point. The role of each fiber is to prevent of spalling effect and improve of flexural strength.

The study is aims at determining mechanical properties of pva fibers reinforced cement composite with recycled materials to overcome problems of plain concrete. The cement composites were evaluated using different ratio of recycled materials

Recently, the use of high strength concrete is increasing in order to increase of high-rise building. High strength concrete has properties that are weak in fire. In severe case, buildings have risk of collapse owing to occur spalling. For these reasons, the authors think it is required to conduct various study about thermal and mechanical properties of high strength concrete in fire. This study analyze thermal and mechanical properties of high strength concrete at elevated temperature to use composite fibers mixed method which is one of method to prevent spalling.

The purpose of this study is to evaluate the effect of improvement on the impact resistance and strength properties of cement composites by surface modification of aramid fiber. For aramid fiber reinforced cement composites, therefore, dispersion capability and the bonding efficiency between the fibers and the cement composite material need to be improved. It is possible by modifying surface properties to hydrophobic, it is considered that oiling agent ratio of 1.2 % and improvement of performance is in need to be investigated. In this study, short aramid fibers were mixed by different fiber length and oiling agent ratio. And improvement of strength properties and impact resistance performance of hybrid cement composites were evaluated under the influence of steel fiber. As a result, strength properties of aramid fiber reinforced cement composites are different by mixing ratio of fiber, oiling agent ratio and length of fiber. In case of cement composites which have same volume fraction and fiber length, tensile strength and flexural strength were improved with increase of the emulsions throughput of the fiber surface. The results of evaluation on the static strength properties had effects on impact resistance performance by high-velocity impact. And it was observed that the scabbing of rear was suppressed with increase of the oiling agent ratio.

Amorphous metal fibers can improve the brittleness of concrete and enhance the shear and tensile strength of reinforced concrete (RC) members. A series of experimental studies RC composite beams with amorphous metal fiber composites were conducted, and it was shown that the RC beam with amorphous metal fiber composites could give improved flexural responses to compare with the reinforced concrete beam.