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Effect of Substituting Normal-Weight Coarse Aggregate on the Workability and Mechanical Properties of Heavyweight Magnetite Concrete

중량 자철석 콘크리트의 유동성 및 역학적 특성에 미치는 보통중량 굵은골재 치환율의 영향

  • Mun, Jae-Sung (Dept. of Architectural Engineering, Kyonggi University Graduate School) ;
  • Mun, Ju-Hyun (Dept. of Architectural Engineering, Kyonggi University Graduate School) ;
  • Yang, Keun-Hyeok (Dept. of Plant.Architectural Engineering, Kyonggi University) ;
  • Lee, Ho (School of Convergence & Fusion System Engineering, Kyungpook National University)
  • 문재성 (경기대학교 일반대학원 건축공학과) ;
  • 문주현 (경기대학교 일반대학원 건축공학과) ;
  • 양근혁 (경기대학교 플랜트.건축공학과) ;
  • 이호 (경북대학교 융복합시스템공학부)
  • Received : 2013.02.15
  • Accepted : 2013.04.15
  • Published : 2013.08.31

Abstract

The objective of this study is to evaluate the workability and various mechanical properties of heavyweight magnetite concrete and examine the reliability of the design equations specified in code provisions. The main parameters investigated were the water-to-cement ratio and substitution level of normal-weight coarse aggregate (granite) for magnetite. The oven-dried unit weight of concrete tested ranged between 2446 and $3426kg/m^3$. The measured mechanical properties included compressive strength development, stress-strain curve, splitting tensile strength, moduli of elasticity and rupture, and bond stress-slip relationship of concrete. Test results revealed that the initial slump of heavyweight magnetite concrete increased as the substitution level of normal-weight coarse aggregate increases. The substitution level of normal-weight coarse aggregate had little influence on the compressive strength and tensile resistance capacity of heavyweight concrete, while it significantly affected the modulus of elasticity and stress-strain curves of such concrete. The design equations of ACI 349-06 and CEB-FIP provisions mostly conservatively predicted the mechanical properties of heavyweight magnetite concrete, but the empirical equations for modulus of elasticity and splitting tensile strength need to be modified considering the unit weight of concrete.

이 연구의 목적은 국내생산이 가능한 자철석을 이용한 중량 콘크리트의 유동성 및 역학적 특성을 평가하고 설계기준의 안전성을 확인하는 것이다. 주요변수로는 물-시멘트 비와 보통중량 굵은골재(화강석)의 치환율이다. 배합된 콘크리트 기건 단위용적질량은 $2446{\sim}3426kg/m^3$ 범위에 있었다. 측정된 역학적 특성들은 압축강도, 응력-변형률관계, 탄성계수, 쪼갬인장강도, 파괴계수 그리고 철근과의 부착응력-미끄러짐 관계 등이다. 실험 결과, 자철석 중량 콘크리트의 초기 슬럼프는 보통중량 굵은골재 치환율이 증가할수록 향상하였다. 압축강도, 인장저항성 등의 역학적 특성은 굵은골재 치환율에 따른 영향이 미미하였으나, 응력-변형률 관계와 탄성계수는 콘크리트 단위용적질량에 중요한 영향을 받았다. ACI 349-06 및 CEB-FIP 제안모델들은 일반적으로 자철석 중량 콘크리트의 역학적 특성들에 대해 안전측에 있지만, 탄성계수 및 쪼갬인장강도에 대해서는 콘크리트 단위용적질량을 고려하여 보완될 필요가 있었다.

Keywords

References

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