CO₂ sequestration in concrete is crucial to relieve the environmental burden, while the carbonation mechanisms remain unclear. Here, we explored the carbonation dynamics of alite hydrates through electron microscopy. We discovered that calcite is the main phase of carbonate crystals throughout the entire carbonation period in alite system. The shape evolution of calcite crystals was captured: our observations revealed that the spindle carbonates initially formed on the C-S-H substrate and then transformed into rhombohedrons; Intermediate states such as polyhedral particles and layered rhomboids were also observed. Based on our quantitative calculations, the growth rate of calcite particles was determined to be approximately 0.2 μm/day, which may be affected by the relative concentration between calcium ions and the CO₂ source. A direct relation between the microstructure and mechanical properties of calcite was uncovered using atomic force microscopy. Furthermore, we found that the morphology development of calcite crystals during carbonation could be explained by the surface energy variation of different facets. This work suggests a unique approach to track carbonation kinetics and provides new opportunities to unveil the underlying carbonation mechanisms at the nanoscale.

二氧化碳_{_}混凝土中的封存对于减轻环境负担至关重要，而碳化机制仍不清楚。在这里，我们通过电子显微镜探索了阿利特水合物的碳酸化动力学。我们发现方解石是阿利特体系整个碳化期碳酸盐晶体的主要相。捕获了方解石晶体的形状演变：我们的观察表明，纺锤状碳酸盐最初在 CSH 基质上形成，然后转变为菱形；还观察到中间状态，例如多面体颗粒和层状菱形。根据我们的定量计算，确定方解石颗粒的生长速率约为 0.2 μm/天，这可能受钙离子和 CO 2 之间的相对浓度的_影响来源。使用原子力显微镜揭示了方解石的微观结构和机械性能之间的直接关系。此外，我们发现方解石晶体在碳化过程中的形态发展可以用不同刻面的表面能变化来解释。这项工作提出了一种跟踪碳化动力学的独特方法，并提供了揭示纳米级潜在碳化机制的新机会。