Journal of the Korean Recycled Construction Resources Institute (한국건설순환자원학회논문집)

Korean Recycled Construction Resources Institute (한국건설순환자원학회)
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Evaluation on Long-term Mechanical Performance and Durability of Recycled Coarse Aggregate Concrete Produced by Two-stage Mixing Approach

2단계 배합방법으로 제조된 순환굵은골재 콘크리트의 장기재령 역학적 성능 및 내구성 평가

  • Seong-Uk, Heo (Divisiont of Architectural and Fire Protection Engineering, Pukyong National University) ;
  • Jeong Jin, Son (Divisiont of Architectural and Fire Protection Engineering, Pukyong National University) ;
  • Chul-Woo, Chung (Department of ArchitecturalEngineering Pukyong National University) ;
  • Young Chan, Kim (Department of ArchitecturalEngineering Pukyong National University)
  • 허성욱 (부경대학교 건축.소방공학부 ) ;
  • 손정진 (부경대학교 건축.소방공학부 ) ;
  • 정철우 (부경대학교 건축공학부 ) ;
  • 김영찬 (부경대학교 건축공학부 )
  • Received : 2022.11.11
  • Accepted : 2022.11.22
  • Published : 2022.12.30
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Abstract

Recycled aggregates show high water absorption rate compared to natural aggregates due to microcrack developed during production process and adhered cement pastes at the surface of recycled aggregates. This leads to the deterioration of mechanical properties and slow work flow. Currently it is getting hard to satisfy high demand for natural aggregates. Utilizing recycled aggregate more widely may be a substitutable countermeasure for the shortage of natural resources. In this study, two-stage mixing approach(TSMA) suggested by Tam et al. is used to produce recycled aggregate concrete(RAC) with 100 % replacement of coarse natural aggregate and tests for compressive strength, elastic modulus, and chloride ion diffusion coefficient are conducted to find out the effect of TSMA compared to normal mixing method. According to experimental result compressive strength and elastic modulus of RAC with TSMA was superior to those of RAC with normal mixing irrespective of water-cement ratio, and in some cases mechanical properties of RAC with TSMA approached to those of natural aggregate concrete(NAC). However, chloride ion diffusion coefficient of RAC was higher than that of NAC. This illustrates that TSMA is not an appropriate method in reducing chloride ion diffusion coefficient, resulting in inconsequential contribution of TSMA to the durability of RAC.

순환골재는 생산과정에서 발생하는 미세균열 및 순환골재 표면에 존재하는 시멘트 페이스트 성분의 존재로 인해, 천연골재에 비해 높은 흡수율을 가지며, 이로 인해 콘크리트에 골재로서 사용할 경우 작업성 저하, 강도의 저하 등의 문제가 발생하게 된다. 골재의 수급이 점점 어려워지고 있는 현 상황에, 골재 수급의 대안이 될 수 있는 순환골재를 적극적으로 활용하기 위한 방법으로, 본 연구에서는 Tam et al.이 제안한 2단계 배합과정을 활용하였고, 이를 이용해 제조한 콘크리트의 압축강도, 탄성계수, 및 염소이온 확산계수를 일반 배합과정을 적용한 천연골재 콘크리트 및 100 % 치환율의 순환골재 콘크리트와 비교 분석하였다. 실험 결과에 따르면, 압축강도와 탄성계수는 물시멘트비에 관계없이, 2단계 배합방법으로 제작한 순환골재 콘크리트가 일반배합과정으로 배합된 순환골재 콘크리트에 비해 높게 나타났으며, 천연골재 콘크리트에 근접하는 역학적 성능을 발휘하였다. 그러나 염소이온 확산계수의 경우 순환골재 콘크리트가 천연골재 콘크리트보다 높게 측정되었으며, 2단계 배합과정의 적용에 따른 염소이온 확산계수의 감소는 확인할 수 없어, 2단계 배합이 내구성에는 크게 기여하지 않는 것으로 판단된다.

Keywords

Acknowledgement

이 논문은 부경대학교 자율창의학술연구비(2021년)에 의하여 연구되었음.

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