한국지반공학회논문집 (Journal of the Korean Geotechnical Society)

  • 제33권4호
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  • Pages.35-46
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  • 2017
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  • 1229-2427(pISSN)
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  • 2288-646X(eISSN)
한국지반공학회 (Korean Geotechnical Society)
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섬유/모래로 보강된 미연소탄소탄소 고함량 플라이애쉬의 지반공학적특성

Geotechnical Characteristics of Fly Ash Containing High Content of Unburned Carbons Reinforced with Fibers and Sand

  • 윤보영 (고려대학교 건축사회환경공학부) ;
  • 이창호 (전남대학교 해양토목공학과) ;
  • 추현욱 (고려대학교 건축사회환경공학부) ;
  • 이우진 (고려대학교 건축사회환경공학부)
  • Yoon, Boyeong (School of Civil, Environmental and Architectural Engrg., Korea Univ.) ;
  • Lee, Changho (Dept. of Marine and Civil Engrg., Chonnam National Univ.) ;
  • Choo, Hyunwook (School of Civil, Environmental and Architectural Engrg., Korea Univ.) ;
  • Lee, Woojin (School of Civil, Environmental and Architectural Engrg., Korea Univ.)
  • 투고 : 2017.02.27
  • 심사 : 2017.04.11
  • 발행 : 2017.04.30
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초록

미연소탄소 함량이 높은 플라이애쉬(High carbon contents fly ash, HCFA)는 콘크리트 혼화재로의 사용이 부적합하여 대부분 매립되고 있다. 이에 본 연구는 미연소탄소함량이 높은 플라이애쉬의 지반공학적 활용 방안을 모색하기 위하여 폴리프로필렌섬유(Polypropylene fiber, PP fiber)와 모래로 보강하여 일축압축시험과 벤더엘리먼트가 설치된 일차원 수정 압축실험을 진행하였다. 섬유의 보강효과로 섬유비가 증가함에 따라 일축압축강도(UCS), 일축압축강도시의 변형률과 동일 간극비 상에서의 최대전단탄성계수(Maximum Shear Modulus, $G_{max}$)가 증가하였다. 모래로 보강된 경우 혼합물의 UCS는 다소 증가하였으나 UCS 시의 변형률은 모래비의 영향을 받지 않았으며, 모래입자는 HCFA 입자간의 접촉을 방해하여 혼합물의 $G_{max}$를 감소시켰다. 그러나 20% 이상의 모래비에 대하여 동일 에너지로 다짐하였을 시, 조밀한 상태로 조성되며 그로 인한 보강 효과를 기대할 수 있었다. 섬유나 모래로 보강된 HCFA의 압축지수(Compression index, $C_c$)는 보강재의 종류와 관계없이 주로 초기 간극비에 의해 결정되었다.

Most of high carbon fly ashes (HCFA) are discarded in landfills with high costs due to low recycling rate. This study aims to explore the geotechnical behaviors of HCFA mixtures reinforced with fiber and sand. A series of compaction test, unconfined compressive strength test and modified 1D consolidation test with bender element were performed. Specimens were prepared at their optimal moisture contents based on the results of compaction tests. The results of this study demonstrate that the inclusion of fibers to the matrix of HCFA increases unconfined compressive strength (UCS), strain at UCS, and maximum shear modulus ($G_{max}$) at a given void ratio. Reinforcement with sand increases UCS of HCFA; while the strain at UCS is irrelevant with sand fractions. Sand particles may disrupt the direct contacts between HCFA particles at low sand content, resulting in a decrease in $G_{max}$. However, it can be expected that the mixtures with sand content larger than 20% are in dense state; thus, $G_{max}$ of HCFA reinforced with sand shows greater value than that of unreinforced HCFA compacted with the same energy. Regardless of types of reinforcement, the compression index ($C_c$) of both fiber and sand reinforced HCFA is mainly determined by initial void ratio.

키워드

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