Abstract The structure of Calcium-Silicate-Hydrate (C-S-H) and the effect of variations in its water content have been investigated using density functional theory (DFT) calculations. Trends for calculated densities as a function of hydration are in good agreement with experimental values, and in line with what is found using molecular mechanics in the literature. While we observe very little variation in Si O and Ca O bond lengths between different structures, structural diversity is otherwise great, in accordance with experimental observations, as we see no obvious correlation between structural features and material system stability. A mapping of energetics of hydroxyl substitution with chloride reveals, unsurprisingly, that chloride preferentially coordinates to calcium. More specifically, it was found that the most stable sites for chlorine substitution involves at least two adjacent calcium atoms. Computed chloride substitution energies indicate that the C-S-H phase may bind chloride from aqueous solution, potentially influencing chloride diffusion in concrete.

中文翻译：

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CSH 中的结构、水合和氯化物进入：来自 DFT 计算的洞察

摘要 使用密度泛函理论 (DFT) 计算研究了硅酸钙 (CSH) 的结构及其含水量变化的影响。作为水合函数的计算密度的趋势与实验值非常一致，并且与文献中使用分子力学发现的结果一致。虽然我们观察到不同结构之间 Si O 和 Ca O 键长的变化很小，但根据实验观察，结构多样性很大，因为我们没有看到结构特征和材料系统稳定性之间存在明显的相关性。毫不奇怪，氯取代羟基的能量图显示，氯化物优先与钙配位。进一步来说，发现氯取代的最稳定位点涉及至少两个相邻的钙原子。计算的氯化物替代能表明 CSH 相可能会结合水溶液中的氯化物，从而可能影响混凝土中的氯化物扩散。