Journal of the Korean Recycled Construction Resources Institute (한국건설순환자원학회논문집)

Korean Recycled Construction Resources Institute (한국건설순환자원학회)
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Carbonation Assessment for Superstructure of Bridge Used in Urban Area for 46-Years by Core Specimens Extracted from the Structure

도심지에서 46년 사용된 교량 상부구조물에서 채취한 코어를 통한 탄산화 실태조사

  • Kwon, Seung-Hee (Department of Civil and Environmental Engineering, Myongji University) ;
  • Kwon, Seung-Jun (Department of Civil and Environmental Engineering, Hannam University)
  • 권승희 (명지대학교 토목환경공학과) ;
  • 권성준 (한남대학교 토목환경공학과)
  • Received : 2019.05.16
  • Accepted : 2019.06.27
  • Published : 2019.06.30
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Abstract

Concrete bridge constructed in metropolitan cities has different superstructure members like slabs and girders, and their carbonation depths vary with different design strengths and local environmental conditions. In this paper, 54 concrete cores were obtained from prestressed concrete girders and the related tests were performed for compressive strength and carbonation depth measurement. Referred to the specified compressive strength of 24MPa for slab and 35MPa for I-type girder, the strengths from cores were evaluated to 82% and 73% of design grade, respectively. For carbonation depth, the slab member showed 30.6mm of average with 32.9% of COV(Coefficient of Variation) and I-type girder showed 16.7~17.0mm with 22.8~33.6 of COV. The I-type girder has much lower carbonation depth and COV compared to slab member, however it has higher COV than column structures.

대도시에 시공된 콘크리트 교량의 경우 상부의 슬래브 및 PSC 거더가 같이 존재하고 있으며 설계 강도 및 국소적인 환경의 변동성으로 탄산화 거동이 다르게 평가된다. 본 연구에서는 46년간 사용된 PSC 거더교에 대하여 54개의 콘크리트 코어를 채취하였으며, 압축강도 및 탄산화 깊이 평가를 수행하였다. 설계 강도 24MPa인 슬래브와 35MPa인 I형 거더에 대하여 코어압축강도는 19.6MPa과 25.4MPa로 평가되어 각각 84% 및 73% 수준으로 조사되었다. 탄산화의 경우 상부에 대해서는 30.6mm의 탄산화 깊이와 32.9%의 높은 변동성을 나타내었다. I형 거더의 경우 상부에 비하여 16.7~17.0mm의 탄산화 깊이와 22.8~33.6%의 변동성을 나타내었다. I형 거더의 경우 상부 슬래브에 비하여 낮은 탄산화 깊이와 변동성을 가지고 있었으나, 하부구조에 비해서 높은 변동성을 가지고 있음을 알 수 있다.

Keywords

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Fig. 1. Superstructure and sectional view used in the experiment

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Fig. 2. Relative humidity and temperature with months(KMA 2019)

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Fig. 3. Photo of PSC–I-Girder for coring(S1, S2, S3)

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Fig. 4. Compressive strength of core

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Fig. 5. Carbonation depth propagation in the target structures

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Fig. 6. Location of carbonation depth devaluation

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Fig. 7. Contour of carbonation depth with locations

Table 1. Environmental conditions for target structure(KMA 2019)

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Table 2. Summary of carbonation progress with the related characteristics

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