This study evaluates the life cycle CO₂ emissions of concrete structures using recycled aggregates to support carbon neutrality in the construction industry. A life cycle assessment (LCA) was conducted on a 12-story reinforced concrete building in Seoul, encompassing stages from raw material extraction, transportation, concrete production, and construction, to a 40-year usage period (accounting for carbonation-induced CO₂ uptake), demolition, and waste processing. The assessment compared major structural members (columns, walls, beams, and slabs) based on two distinct environmental impact inventory categories: the 'Upper Level' (reflecting production process uncertainties) and the 'Lower Level' (assuming high-efficiency, optimized manufacturing processes). The results reveal a dual-faceted environmental impact of recycled aggregates. Under Upper Level conditions, the recycled aggregate concrete mixes increased life cycle CO₂ emissions by 25% to 34% compared to standard conventional concrete due to high material emission coefficients. Conversely, under Lower Level conditions, recycled aggregate concrete achieved comparable or reduced CO₂ emissions compared to conventional mixes. The findings demonstrate that to successfully implement low-carbon designs using recycled aggregate concrete, technical advancements must focus on controlling energy consumption during the aggregate production and refining processes to stabilize inventory data at the Lower Level.

Abstract
1. 서론
2. 순환골재 콘크리트 구조물의 전과정CO2 배출량 평가 절차
    2.1 공정별 시스템 경계
    2.2 전과정 CO2 배출량 평가 절차
3. 구조물의 전과정 CO2 배출량 평가
    3.1 사례연구 대상
    3.2 전과정 CO2 배출량 평가 예시
4. 각 부재별 CO2 배출량 평가
    4.1 기둥 부재의 CO2 배출량 평가
    4.2 벽체 부재의 CO2 배출량 평가
    4.3 보 부재의 CO2 배출량 평가
    4.4 슬래브 부재의 CO2 배출량 평가
5. 결론
References

• 정연백(청운대학교 건축공학과 조교수, 공학박사) | Jung Yeon-Back (Dept. of Architectural Engineering, Chungwoon University)