Abstract The hydration of calcium silicate phases dominates the application of cement clinkers and has important practical implications. The reaction mechanisms between water and calcium silicate phases are complex and remain poorly understood at the atomic level. Herein, the single water adsorption on all low-index surfaces of β-C2S and M3-C3S was investigated using DFT-D calculations. The surface energy was calculated and the influence of surface cleavage discussed. Both dissociative and molecular adsorptions were investigated. Molecular adsorption was energetically favoured on β-C2S surfaces while dissociative adsorption was energetically favoured on M3-C3S surfaces. A Wulff construction was used to describe the equilibrium morphology with and without an adsorbed water molecule for the β-C2S phase. Water adsorption promoted the solid dissolution by weakening the bond among surface atoms. Electron transfer was observed mainly from the surface atoms to water atoms during the adsorption. These findings provide a novel insight into the adsorption of a water molecule on different calcium silicate surfaces using the same level of theory, which includes a representation of van der Waals forces, therefore, laying the foundation for better understanding the hydration mechanism.

中文翻译：

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水泥中硅酸钙相低指数表面单水吸附的 DFT-D 研究

摘要 硅酸钙相的水化在水泥熟料的应用中占主导地位，具有重要的实际意义。水和硅酸钙相之间的反应机制很复杂，在原子水平上仍然知之甚少。在此，使用 DFT-D 计算研究了 β-C2S 和 M3-C3S 的所有低指数表面上的单一水吸附。计算表面能并讨论表面解理的影响。研究了解离和分子吸附。β-C2S 表面有利于分子吸附，而 M3-C3S 表面有利于解离吸附。Wulff 结构用于描述 β-C2S 相在有和没有吸附水分子的情况下的平衡形态。水吸附通过削弱表面原子之间的键来促进固体溶解。在吸附过程中主要观察到从表面原子到水原子的电子转移。这些发现提供了使用相同理论水平对水分子在不同硅酸钙表面吸附的新见解，其中包括范德华力的表示，因此，为更好地理解水合机制奠定了基础。