The Journal of the Korea Contents Association (한국콘텐츠학회논문지)

The Korea Contents Association (한국콘텐츠학회)
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Modeling on Ultrasonic Velocity in Concrete Considering Micro Pore Structure and Loading Conditions

공극구조 및 하중조건에 따른 콘크리트의 초음파 속도 모델링

  • Received : 2014.11.19
  • Accepted : 2014.01.20
  • Published : 2015.03.28
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Abstract

For a long time, evaluation of soundness and strength in concrete has been performed through ultrasonic velocity(UV), which is essential work in field assessment. Porosity in concrete is a major parameter indicating durability and strength, and UV passing concrete depends on porosity variation. In this paper, a modeling on UV through concrete is carried out considering porosity and the results are verified with those from test. Additionally UV in concrete under compression/tension loading condition is measured and UV modeling with loading condition is performed. Up to 50% of loading ratio, UV slightly increases and greatly drops at peak load in compression region, however it fluctuates in tensile region due to micro cracking in matrix. The proposed model shows a reasonable agreement with test results in control and compression region, and needs modification for tensile region considering micro cracks and local aggregate interlocking.

초음파 속도를 이용한 콘크리트의 건전성 및 강도평가는 오랫동안 사용되어 왔으며, 현장조사에서 필수적이다. 콘크리트 내부의 공극률은 내구성 및 강도를 평가할 수 있는 주요인자이며, 초음파 진행에 방해가 되므로 공극률 변화에 따라 초음파 속도변화가 발생한다. 본 연구에서는 기존의 공극률 모델을 이용하여 콘크리트 내부를 통과하는 초음파 속도 모델링을 수행하였으며 실험값과의 비교하였다. 또한 인장 및 압축 재하 시험과 동시에 초음파 속도를 측정하여 재하 하중비를 이용한 모델링을 수행하였다. 압축영역에서는 하중재하비 50% 수준까지 초음파 속도가 약간 증가하였으며, 최대하중에 근접할수록 급격한 속도의 감소가 발생하였다. 인장영역에서는 압축영역과 다르게 초기부터 초음파 속도가 상당히 변화하였다. 제안된 기법은 콘크리트의 건전부 및 압축영역에서는 합리적인 결과를 보이고 있으며 인장영역에서는 미세균열 및 국소적인 골재치합을 고려한 보완이 필요할 것으로 판단된다.

Keywords

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