최근 지구온난화로 인해 발생하는 극단적인 기상현상이 빈번해짐에 따라, 사회 인프라와 건축물의 노후화로 인한 붕괴 위험이 증가 하고 있다. 이러한 문제를 해결하기 위해 본 연구는 구조물 유지보수 및 보강을 위한 고성능 숏크리트 공법을 개발하는 것을 목표로 한다. 특히, 자연섬유와 나노버블수를 혼입한 숏크리트는 콘크리트의 성능을 크게 향상시킬 수 있는 잠재력을 가지고 있다. 자연섬유 는 콘크리트의 점착력과 부착력을 높여 펌핑성과 유동성을 개선하고, 콘크리트 내부에 수분을 지속적으로 공급하여 소성수축 균열을 억제하는 효과가 있다. 이를 통해 구조물의 내구성을 증진시키며, 공용 수명을 연장하는 데 기여한다. 또한, 나노버블수는 콘크리트의 수화 반응을 촉진하여 응결 시간과 초기 강도를 크게 향상시킨다. 나노버블수는 콘크리트 혼합물 내에서 슬립 현상을 제공하여 리바 운드를 저감시키고, 시공 중 발생하는 재료 손실을 줄여 시공 효율성을 높이는 역할을 한다. 나아가, 나노버블수는 이산화탄소를 포집 하여 생성할 수 있어 탄소 배출을 줄이는 환경적 이점을 제공하며, 급결제 사용을 줄여 환경오염 감소에도 기여한다. 본 연구에서는 다양한 실험을 통해 각 변수의 영향을 분석하였다. 결론적으로, 자연섬유와 나노버블수를 혼입한 고성능 숏크리트를 통해 구조물 보수 및 보강 공사에서 비용을 절감하는 동시에, 내구성을 크게 향상시킬 수 있음을 증명하고자 한다. 이 연구 결과는 향후 다양한 구조물 유지 보수 공법에 적용될 수 있으며, 건설 산업에서 지속 가능한 기술로 자리 잡을 것으로 기대된다.

In order to improve the durability of the asphalt pavement, the glass fiber reinforced asphalt which reinforces the aggregate and the binder in three - dimensional form by adding glass fiber to the asphalt mixture has been studied and the durability improvement effect of the asphalt pavement has been confirmed. Porous pavement has been increasingly applied due to reduced traffic accidents and noise reduction, but durability problems such as aggregate stripping and pot-hole are emerging. This study evaluated the durability enhancement effect by adding glass fiber to the porous mixture. The cantabro loss ratio and the indirect tensile strength test were performed to evaluate the performance of the glass fiber reinforced porous mixture. The glass fibers were added to the mixture using PG76-22 and PG64-22 binder and not to the mixture using PG82-22 binder. The mixture using the PG76-22 binder was added 1.4% (PEGS 0.6%, Micro PPGF 0.2%, Macro PPGF 0.6%) glass fiber based on the weight of the mixture. The mixture using the PG64-22 binder was added 1.4% (PEGS 0.6%, Micro PPGF 0.2%, Macro PPGF 0.6%) and 2.1% %(PEGS 0.9%, Micro PPGF 0.3%, Macro PPGF 0.9%)glass fibers by weight of the mixture. The glass fibers were used at the same ratio as that applied to the conventional asphalt mixture test. As a result of the cantabro loss rate test, the mixture using the PG82-22 binder showed a loss rate of 10.7% at 20 ℃ and 22.4% at -20 ℃. The mixture using PG76-22 binder and 1.4% glass fiber showed a loss ratio of 13.2% at 20 ℃ and 26.7% at -20 ℃. The mixture using PG64-22 binder and 1.4% glass fiber showed a loss rate of 12.5% at 20 ℃ and 35.9% at -20 ℃. The mixture using PG64-22 binder and 2.1% glass fiber showed a loss rate of 11.9% at 20 ℃ and 26.6% at -20 ℃. The three mixtures (using of PG82-22 binder, PG76-22 binder + 1.4% glass fiber and PG64-22 binder + 2.1% glass fiber) satisfied quality standard of Ministry of Land, Infrastructure and Transport. As a result of the indirect tensile strength test, the mixture using the PG82-22 binder showed 0.73 N/㎟. The mixture using PG76-22 binder and 1.4% glass fiber showed 0.88 N/㎟. The mixture using PG64-22 binder and 1.4% glass fiber showed 0.62 N/㎟. The mixture using PG64-22 binder and 2.1% glass fiber showed 0.74 N/㎟. In this study, the durability enhancement effect was confirmed by adding glass fiber to the drainage mixture. We will do further research to confirm the optimal combination of glass fibers.

Silicon carbide whiskers (SiCw) having the diameter in the range of 20-80 nm were synthesised from coconut fibres through sol-gel process. The coconut fibres were impregnated with tetraethoxysilane and methyltriethoxysilane derived sol and pyrolyzed at 1400℃ in argon. X-ray of the pyrolyzed samples showed the formation of β-SiC.

Sixteen clinically healthy New Zealand white rabbits of either sex were divided into two equal groups I and II of 8 animals each. Under thiopental sodium (2.5%) anaesthesia a linear full thickness abdominal wall defect of 3 cm in length was created and repaired with continuous suture pattern using 3000 filaments of carbon fibres and 1~0 black braided nylon suture, ingroup I and II respectively. Increased vascularity was observed in carbon fibres (group I) and on day 30 the carbon fibres were covered by white fibrous tissue. Significantly higher (P < 0.05) values of glucose was seen on day 14 in group I, whereas, decrease in glucose value was observed in group II. Histopathologically, the carbon fiber implant induced extensive fibrous tissue (collagen fiber) reaction. Negligible inflammatory cells in the stroma indicate the host tissue tolerance to carbon fibers. Histochemically, gradually increased alkaline phosphatase activity up to day 14 in group I, suggested the proliferation of fibroblasts in early stages.

A study of partial carbonisation of green pitch fibres to temperatures in the range of 500-1000℃ was carried out on three precursors - a neat pitch and two polymer modified pitches, with a view to find out a suitable temperature at which the fibres acquire considerably improved toughness or handleability (compared to that in the green stage) for their subsequent processing into carbon fibres. A partial carbonisation temperature of 500-600℃ has been identified to result in a remarkable improvement in the toughness/handleability of the fibres in all the three cases. However, from techno-economical considerations, the neat pitch appears to provide the best precursor system for the production of pitch based carbon fibres.

Asbestos is being replaced throughout the world among friction materials because of its carcinogenic nature. This has raised an important issue of heat dissipation in the non-asbestos brake pad materials being developed for automobiles etc. It has been found that two of the components i.e. carbon fibres as reinforcement and graphite powder as friction modifier, in the brake pad material, can playa vital role in this direction. The study reports the influence of these modifications on the thermal properties like coefficient of thermal expansion (CTE) and thermal conductivity along with the mechanical properties of nonasbestos brake pad composite samples developed in the laboratory.