An innovative strategy for maximizing CO₂ reduction in concrete through preparing carbon sequestration precursors by accelerated carbonation

Concrete possesses significant potential as a medium for CO₂ sequestration. Nevertheless, conventional approaches like CO₂ mixing and carbonation curing have shown limited efficacy in this regard. The present work introduces a groundbreaking method for enhancing CO₂ reduction in concrete production. It involves preparing carbon sequestration precursors (CSP) through carbonation of cement reinforced by mechanochemical effects. The study investigated the kinetics and phase assemblage during the CSP production process, along with examining the impact of CSP on the reaction kinetics and strength development of cement composites. Due to the mechanochemical effects, CSP was characterized by the prevalence of metastable calcium carbonate (Cc) with a small crystalline size. Moreover, CSP not only accelerated the hydration of cement composites but also led to increased compressive strength at all ages, even with the replacement of 30 wt% of cement by CSP. The multifunctional attributes of CSP, including nucleation, reactant, and inert filler roles, contributed to its exceptional performance. Furthermore, utilizing the CSP method demonstrated a significant capacity for CO₂ reduction, exceeding 36.5 %, which is more than seven times that of the traditional CO₂ mixing method. The positive outcomes from this study underscore the high efficacy of the CSP method for efficient CO₂ sequestration in concrete.