Precast concrete components are widely utilized in the construction industry owing to their controllable quality and high construction efficiency. Steam curing effectively accelerates early strength development; to further enhance the mechanical performance of precast elements under identical curing regimes, this study proposes a novel approach involving pre-carbonation treatment to provide crystal nuclei for the subsequent steam curing process. By refining the pore structure and increasing microstructural compactness, this method yields a notable improvement in compressive strength. A comprehensive suite of analytical techniques-including ICP, XRD, SEM-EDS, LF-NMR, and nanoindentation-was employed to systematically elucidate the influence of pre-carbonation on the evolution of hydration products and the microstructural characteristics of concrete, thereby revealing its governing effects on both workability and mechanical properties. The results demonstrate that pre-carbonation consumes a fraction of C₃S and C₂S while promoting the formation of calcium carbonate; this reaction reaches a near‑steady state within 20 min. The incorporation of glutamic acid effectively induces the preferential formation of the vaterite polymorph. Furthermore, pre-carbonation shortens setting times and exhibits a synergistic acceleration effect when combined with glutamic acid. In terms of mechanical performance, pre-carbonation significantly enhances early-age strength, with the glutamic acid‑modified group showing strength increases ranging from 21.4 % to 30.8 % between 12 h and 7 d. Microstructural analyses confirm that the in-situ generation of calcium carbonate contributes to pore refinement and improved matrix densification. In summary, pre‑carbonation treatment enables strength enhancement without prolonging the steam curing duration, thereby offering both substantial environmental benefits and considerable potential for performance optimization.