Journal of the Korea institute for structural maintenance and inspection (한국구조물진단유지관리공학회 논문집)

Korea Institute for Structural Maintenance Inspection (한국구조물진단유지관리공학회)
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Simplified Carbonation Model Considering Ca(OH)2 Solubility and Porosity Reduction

수산화칼슘 용해도와 공극률 감소를 고려한 간략화 된 탄산화 모델

  • 이윤 (대전대학교 토목공학과) ;
  • 권성준 (한남대학교 건설시스템 공학과) ;
  • 박기태 (한국건설기술연구소)
  • Received : 2014.05.22
  • Accepted : 2014.09.26
  • Published : 2015.01.30
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Abstract

Carbonation is one of the most critical deterioration phenomena to concrete structures exposed to high $CO_2$ concentration, sheltered from rain. Lots of researches have been performed on evaluation of carbonation depth and changes in hydrate compositions, however carbonation modeling is limitedly carried out due to complicated carbonic reaction and diffusion coefficient. This study presents a simplified carbonation model considering diffusion coefficient, solubility of $Ca(OH)_2$, porosity reduction, and carbonic reaction rate for low concentration. For verification, accelerated carbonation test with varying temperature and MIP (Mercury Intrusion Porosimetry) test are carried out, and carbonation depths are compared with those from the previous and the proposed model. Field data with low $CO_2$ concentration is compared with those from the proposed model. The proposed model shows very reasonable results like carbonation depth and consuming $Ca(OH)_2$ through reduced diffusion coefficient and porosity compared with the previous model.

탄산화는 지하구조물과 같이 이산화탄소의 농도가 높고 강우로부터 보호되는 콘크리트 구조물에 매우 심각한 열화현상이다. 탄산화 깊이 및 수화물의 변화를 평가하기 위해 많은 연구가 진행되고 있으나 해석모델의 복잡성, 이산화탄소 확산계수 모델링 등의 어려움으로 인해 실제 탄산화 거동을 제한적으로 모사하고 있다. 본 연구에서는 기존의 탄산화 모델링 (Ducom)에 대하여 확산계수 모델링, 공극률 감소 모델, 이산화탄소의 장기반응률 등을 개선하여 개선된 탄산화 모델을 제시하였다. 검증을 위하여 온도변화를 고려한 촉진탄산화 시험. 공극률 평가 시험 (수은압입법)을 수행하였으며, 탄산화 깊이를 개선되기 전/후의 모델과 비교하였다. 또한 수산화칼슘의 중량변화와 실태조사결과를 이용하여 낮은 이산화탄소에 노출된 콘크리트 구조물의 탄산화 깊이를 제안된 모델과 비교하였다. 제안된 모델은 확산계수 감소성, 공극률 감소성을 적절하게 반영하여 기존의 모델에 비해 합리적인 결과 (수산화칼슘 소모량, 탄산화 깊이)를 나타내었다.

Keywords

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  1. 탄산화 중심의 콘크리트 구조물 내구성 설계 vol.27, pp.5, 2015, https://doi.org/10.22636/mkci.2015.27.5.21