Journal of the Korean Industrial and Engineering Chemistry, Vol.11, No.7, 785-791, November, 2000
콘크리트중의 염소이온 확산계수 측정을 위한 촉진 시험법
Accelerated Test for the Measurement of Chloride Diffusion Coefficient in Concrete
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초록
전기장을 이용하여 콘크리트내의 염소이온 확산계수를 짧은 기간내에 측정할 수 있는 촉진 시험법이 제시되었다. 순수 확산셀 방법을 변형한 Dhir의 실험장치를 이용하되, 일차원 물질전달에 적용되는 Nernst-Planck 방정식과 mass flux의 정의로부터 새롭게 제안된 콘크리트내의 염소이온 확산 계수 계산모델을 적용하였다. 촉진 시험을 위한 적정 조건을 찾아내기 위하여 시편의 두께, 전위차 및 수조의 염소이온 농도에 의한 영향을 고찰한 결과 시편 두께 30 mm, 전위차 10 V 및 수조의 염소이온 농도가 5M 가 적정하다고 판단되었다. 이와 같이 결정된 실험 조건과 제안된 확산계수 계산모델을 이용하여 보통포틀랜드 시멘트를 사용한 콘크리트에 대하여 염소이온 확산계수를 계산하였다. 계산된 확산계수의 신뢰성을 검증하기 위해 순수 확산실험에 의하여 염소이온 확산계수를 측정하여 비교한 결과 촉진 시험 결과 동일한 자리수대의 값을 보였을 뿐 아니라 직선적인 상관관계를 보여 제안된 모델의 적정성을 확인시켜 주었다.
An accelerated test method using electric field is proposed to measure chloride diffusion coefficient in concrete in a short period. Dhir's test set-up modified from conventional diffusion cell method and a novel diffusion coefficient analysis model proposed from the definition of steady-state mass flux and the Nernst-Planck Equation applicable to one-dimensional mass transfer were used. From the investigation of effects of sample thickness, applied electrical potential difference and the bulk chloride concentration, it was concluded that 30 mm of sample thickness, 10 volts of potential difference and 5 M of chloride ion concentration constituted an optimal experimental condition. Chloride diffusion coefficients were measured under the optimal experimental condition using the proposed diffusion coefficient analysis model. Comparison of these results with those by the conventional diffusion cell test confirmed the reliability of the method.
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