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Chloride Diffusion Coefficient Model Considering the Initiation Time of Exposure to Chloride Environment

염소이온 노출개시시기를 고려한 기존 확산계수 모델 수정제안

  • Kim, Ki-Hyun (Research Institute of Energy And Resources, Seoul National University) ;
  • Cha, Soo-Won (Dept. of Civil and Environmental Engineering, University of Ulsan)
  • 김기현 (서울대학교 에너지자원신기술연구소) ;
  • 차수원 (울산대학교 건설환경공학부)
  • Published : 2009.06.30

Abstract

A reference diffusion coefficient model from ACI life-365 is drawn from test results by NT build 443. This test method gives a time-averaged diffusion coefficient during immersion period, thus the ACI model uses the time-averaged diffusion coefficient as a reference value. ACI model needs to be revised, considering the difference between the time-average value and reference value at specified time. In this study, firstly the analytic solutions of diffusion equation are derived considering the initiation time and period of exposure to chloride, and secondly the time-averaged diffusion coefficient from NT build 443 is converted into the diffusion coefficient at reference time. From this study, the reference diffusion coefficient of ACI model should be modified to be about 10% larger values than those of present ACI model. For convenient design of service life, previous relationship between the chloride diffusion coefficient from NT build 443 and that from NT build 492 is also modified. To compare the chloride diffusion coefficients of ACI and JCI models, the reference chloride diffusion coefficient with respect to the JCI model is drawn in the similar form of ACI model's, and service life prediction by ACI life-365 method is confirmed to give a conservative result.

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