Enhancing Steel Slag Cementitious Performance: The Role of CO ₂ Mineralization

ABSTRACT CO 2 mineralization of alkaline solid wastes enables permanent CO 2 sequestration and the production of cementitious materials. However, the inherently low reactivity of these wastes limits their practical application. This study systematically investigates the impact of CO 2 mineralization on steel slag's cementitious activity and develops targeted enhancement strategies. By constructing a comprehensive database integrating experimental and literature data, we employed XGBoost‐based machine learning to quantitatively evaluate reactivity‐limiting factors. Key findings reveal that while CO 2 mineralization minimally directly enhances reactivity, it critically improves slag stability and mitigates risks from trace elements. Subsequent thermodynamic and kinetic studies identified mechanochemical milling and aluminate incorporation as effective methods for boosting slag reactivity. To improve slag performance, we recommend optimizing particle size to ≤ 20 µm, applying magnetic separation to limit iron content to ≤ 30 wt%, and integrating mechanochemical milling for enhanced activation.