This study investigated the effect of accerelated carbonation on the pore structure of fly ash (FA) blended cement paste, focusing on FA replacement ratio and curing age. Cement paste specimens with FA replacement ratios of 15, 45, and 65% were cured for 35 and 112 days and subjected to accelerated carbonation. The capillary and gel porosity were separately measured using an oven-drying method, and the phase assemblage was quantified by Rietveld refinement of XRD data. In addition, the stoichiometric volume change due to carbonation was estimated based on the Ca/Si ratio of the CSH, which varies with the fly ash replacement ratio and curing days. After carbonation, the capillary porosity decreased in all mixtures, whereas the gel porosity exhibited contrasting behavior depending on the curing age, increasing in the FA15 and FA45 specimens cured for 112 days. Although the estimated stoichiometric volume increase occurred in all mixtures, its amount did not directly correspond to the measured porosity change, especially in the specimens cured for 112 days. These results indicate that the carbonation-induced pore structure change is governed not solely by the total stoichiometric volume increase but by whether pore filling by carbonation products (CaCO₃and silica gel) or the pore formation associated with gel structure reorganization dominates. In particular, in high-replacement FA systems, carbonation-induced pore structure changes should not be interpreted as simple pore densification by CaCO₃formation.

Abstract
1. 서론
2. 실험 계획 및 방법
    2.1 재료 및 실험 변수
    2.2 실험 방법
3. 실험 결과
    3.1 공극률 측정 결과
    3.2 XRD 결과
4. 결과 분석 및 고찰
    4.1 화학량론에 기반한 CSH의 탄산화로 인한 부피 변화 추정
    4.2 탄산화 생성물의 부피 변화가 공극률에 미치는 영향
5. 결론
감사의 글
References

• 주효은(서울시립대학교 건축공학과 조교수, 공학박사) | Joo Hyo Eun (Dept. of Architectural Engineering, University of Seoul)
• 강진석(서울시립대학교 건축공학과, 석사과정) | Kang Jin Seok (Dept. of Architectural Engineering, University of Seoul)
• 조원정(히로시마대학교 조교수, 공학박사) | Cho Won Jung (Dept. of Civil and Environmental Engineering, Hiroshima University, Japan) Corresponding author