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섬유혼입공법을 적용한 고강도콘크리트 기둥의 비재하 내화시험

Fire Test of Fiber Cocktail Reinforced High Strength Concrete Columns without Loading

  • 염광수 (GS건설(주) 기술연구소 연구개발팀) ;
  • 전현규 (GS건설(주) 기술연구소 연구개발팀) ;
  • 김흥열 (한국건설기술연구원 화재및설비연구센터)
  • Youm, Kwang-Soo (Research Development Team, GS E&C Research Institute, GS E&C) ;
  • Jeon, Hun-Kyu (Research Development Team, GS E&C Research Institute, GS E&C) ;
  • Kim, Heung-Youl (Fire & Engineering Services Research Center, Korea Institute of Construction Technology)
  • 발행 : 2009.08.31

초록

화재시 고강도콘크리트의 폭렬현상을 막고 내부철근 온도의 상승을 억제하기 위하여 폴리프로필렌섬유와 강 섬유를 동시에 사용하는 섬유혼입공법을 제안하였다. 섬유혼입공법을 40~100 MPa 고강도콘크리트 배합에 적용하여 가 열재하방법으로 열적특성을 평가한 후 내화성능을 평가하기 위하여 구조부재에 내화시험을 실시하였다. 2기의 기둥시 험체를 제작하여 ISO 834 표준내화곡선에 따라 180분 비재하 내화시험을 실시하였다. 폭렬은 발생하지 않았으며, 표면 부의 색은 분홍색을 띤 회색으로 변했다. 깊이 60 mm부터 내부 콘크리트의 온도가 급감하였으며, 60분 가열 후 온도구 배는 보통콘크리트보다 5배 적은 2.2oC/mm로 측정되었다. 180분 내화시험 후의 최종온도는 모서리철근이 488.0oC, 중앙 철근이 350.9oC이며, 철근의 총 평균온도는 419.5oC이다. 모서리철근과 중앙철근의 평균온도차는 137.1oC였다. 가열 후 100~150oC부근에서 콘크리트와 철근의 온도상승추세가 변하는데 이는 강섬유와 폴리프로필렌섬유를 혼입한 콘크리트의 온도구배가 낮고, 철근으로의 수분이동과 내부 수분의 막힘현상, 그리고 수분의 기화열 때문이다.

To prevent the explosive spalling of the high strength concrete and control the rise of temperature in the steel rebar during fire, a fiber cocktail method has been proposed simultaneously with the use of polypropylene and steel fiber. After applying the fiber cocktail (polypropylene and steel fibers) into the mixture of high strength concrete with a compressive strength of between 40 and 100 MPa and evaluating the thermal properties at elevated temperatures, the fire test was carried out on structural members in order to evaluate the fire resistance performance. Two column specimens were exposed to the fire without loading for 180 minutes based on the standard curve of ISO-834. No explosive spalling has been observed and the original color of specimen surface was changed to light pinkish grey. The inner temperature of concrete dropped rapidly starting from 60mm deep. After 60 minutes of exposure to the fire, the temperature gradient of fiber cocktail reinforced high strength concrete was measured as 2.2oC/mm, which is approximately 5 times less than that of normal concrete. The final temperatures of steel rebar after 180 minutes of fire test resulted in 488.0oC for corner rebar, 350.9oC for center rebar, and 419.5oC for total mean of steel rebar. The difference of mean temperature between corner and center rebar was 137.1oC The tendency of temperature rise in concrete and steel rebar changed between 100oC and 150oC The cause of decrease in temperature rise was due to the water vaporization in concrete, the lower temperature gradient of the concrete with steel and polypropylene fiber cocktails, the moisture movement toward steel rebars and the moisture clogging.

키워드

참고문헌

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피인용 문헌

  1. Composition Changes in Cement Matrix of RC Column Exposed to Fire vol.26, pp.3, 2014, https://doi.org/10.4334/JKCI.2014.26.3.369
  2. Fire Resistance Performance Test of High Strength Concrete by Type of Mineral Admixture vol.15, pp.6, 2015, https://doi.org/10.5345/JKIBC.2015.15.6.597
  3. Fire Resistance Performance of High Strength Concrete Columns with Fireproof Gypsum Board vol.22, pp.2, 2010, https://doi.org/10.4334/JKCI.2010.22.2.229