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탄소나노튜브와 나노실리카의 혼입량 변화가 고온에 노출된 시멘트 페이스트의 역학적 성능 회복에 미치는 영향
서형원 ( Suh Heongwon ),지현석 ( Jee Hyeonseok ),박태훈 ( Park Taehoon ),배성철 ( Bae Sungchul ) 한국건축시공학회 2019 한국건축시공학회 학술발표대회 논문집 Vol.19 No.2
When concrete is exposed to fire, the decomposition of Portland cement paste results in critical damage to the concrete structure of a building. However the recovery process of the damaged concrete structure has not yet been fully elucidated. In addition, research on appropriate additives such as carbon nanotube (CNT) and nanosilica has been increasing recently, however, investigation of CNT and nanosilica incorporated cement paste after decomposition of CNT by high temperature is not fully investigated. In this study, we investigated the physicochemical properties of CNT incorporated cement paste under different temperatures (200℃, 500℃ and 800℃). Also, the effects of different rehydration conditions (20℃ 60% RH and in water for different curing times) on the recovery of the paste were studied. The changes in tensile strength, surface observation of the specimens were characterized. In addition, the decomposition and formation of hydrates in the paste due to the heating process were studied using X-ray diffraction. The results showed that incorporation of nanosilica enhanced tensile strength after heating to each target temperatures.
원자짝 분포함수를 이용한 순수 C3S 경화체의 고온 노출 시 나노 구조에 관한 연구
지현석 ( Jee Hyeonseok ),서형원 ( Suh Heongwon ),박태훈 ( Park Taehoon ),배성철 ( Bae Sungchul ) 한국건축시공학회 2019 한국건축시공학회 학술발표대회 논문집 Vol.19 No.2
When the cement paste in concrete is exposed to high temperatures, the mechanical performance decreases due to a series of reactions inside the cement. In this study, we investigated the change of nanostructure of C3S when C3S was exposed to high temperature using pair distribution function (PDF) based on high energy X-ray scattering. As a result of X-ray diffraction, there was no significant difference when C3S was heated at 300℃, but most of Ca(OH)2 was decomposed into CaO at 500℃. In addition, it was confirmed that CaO is dominant in the nanostructure when C3S is heated to 500°C.
Computation of Hypersonic Inviscid Flow of low dendsity
Park, Taehoon,Kim, Pok-Son 국민대학교 2003 기초과학연구소 논문집 Vol.22 No.-
We consider two dimensional steady state inviscid flow of air around flying objects including chemical reactions. We present the result of numerical computations of nonequilibrium hypersonic inviscid flow of low density. The model problem is based on the Euler equations and a chemical reaction model accounting for the finite rate reactions. We obtained detailed detailed description of flow properties near the shock and body.
Nonequilibrium Hypersonic Inviscid Flow of High Density around Flying Bodies
Park, Taehoon,Kim, Pok-Son 국민대학교 2002 기초과학연구소 논문집 Vol.21 No.-
We consider two dimensional steady state inviscid flow of air around bodies including chemical reactions. We present numerical results of nonequilibrium hypersonic inviscid flow of high density. The model problem is based on the Euler equations and a chemical reaction model accounting for the finite rate reactions. We obtained detailed detailed description of flow properties near the shock and body.