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박연동 慶山大學校 2000 論文集 Vol.18 No.1
In this study, several rheological properties of binder pastes and concrete are investigated for the development of commercially available fly ash self-compacting high performance concrete. Fly ash contents with 5 levels (0, 10, 20, 30, 40%) blast-furnace slag contents with 6 levels (0, 5, 15, 25, 35, 45%), and water-binder ratios with 4 levels (30, 33, 36, 39%) are selected for test variables to evaluate the self-compacting characteristics of binder pastes. For the estimation of the workability of self-compacting concrete, slump flow, O-funnel time, difference of box height, and L-flow are measured and compared. As the results, the flow is decreased and the viscosity is increased with increasing fly ash content. Self-compacting high performance concrete is successfully produced with 30% fly ash replacement.
플라이애쉬의 품질 변화가 콘크리트의 성질에 미치는 영향
박연동 慶山大學校 1999 論文集 Vol.17 No.1
In this study, effects of carbon content and fineness of fly ash on the workability and the strength development of concrete are investigated experimentally. Carbon content with 6 1eve1s(0, 2, 3 4 5 7%) and fineness with 3 1eve1s(4000, 5000. 6000 cm2/g) are selected for test variables. Besides, the effect of fly ash with variation of initial concrete temperature is tested. The fly ash used in this study is produced from combustion of bituminous coals at Boryong thermal power plant in Korea, and conforms to the quality requirements for KS L 5405. To measure slump and air losses, a small laboratory agitator was used. Slump and air content were measured at 0, 20, 40, and 60 minutes after completion of mixing. All specimens for compressive strength were casted in 100 x 200 mm cylinder moulds and cured in a water chamber at 20±3℃ during the required periods. As the results, the used AE admixture content to maintain constant initial air content is increased linearly with increasing carbon content in the fly ash. With increasing fineness of fly ash, the strengths at 3 and 7days are slightly increased, however, there is no clear difference between28 day strengths within the scope of this study.
강섬유를 보강한 자기충전 콘크리트의 휨 성능 평가를 위한 실험 연구
박연동 한국구조물진단유지관리공학회 2009 한국구조물진단유지관리공학회 논문집 Vol.13 No.6
강섬유보강 자기충전 콘크리트의 휨 성능을 평가하기 위하여 실험을 중심으로 한 연구를 수행하였다. 보 시험체를 만들기 위하여 3종류의 강섬유보강 콘크리트로 7개의 슬래브를 제작하였으며, 일정 기간 양생 후 다이아몬드 날이 달린 절단기로 슬래브를 절단하여 1개의 슬래브 당 5개의 보 시험체를 획득하였다. 각 보 시험체의 하중-처짐 곡선은 변위조절방식을 사용하여 구하였다. 실험 결과, 자기충전 콘크리트는 휨강도 및 연성, 인성지수 등 휨 성능을 평가하는 모든 부분에서 일반 콘크리트보다 양호한 성능을 보여주었다. 결과적으로 다짐이 필요없는 강섬유보강 자기충전 콘크리트는 강섬유보강 콘크리트의 가장 큰 단점인 시공성 저하 문제를 획기적으로 개선할 뿐만 아니라 역학적 성질도 양호하여 향후 토목․건축 분야에서 폭넓게 활용될 수 있을 것으로 생각된다. An experimental study was carried out to estimate the flexural performance of steel fiber- reinforced self-compacting concrete. Seven slabs with three different steel fiber-reinforced concretes were prepared to make beam specimens. After proper curing period, each slab was cut to five beams with a diamond saw. The beam specimen was tested with displacement control method to obtain load-deflection curve. As the results, the self-compacting concrete beam showed higher flexural strength, ductility and toughness index compared to the normal concrete beam. This means that steel fiber-reinforced self-compacting concrete can be used more widely in the field of architecture and civil engineering because of its self-compactability and good mechanical properties.