29Si NMR in Cement: A Theoretical Study on Calcium Silicate Hydrates
29Si NMR in Cement: A Theoretical Study on Calcium Silicate Hydrates
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DOI：
10.1021/jp302218j
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发表时间：
2012-04
影响因子：
3.7
通讯作者：
Paweł Rejmak;J. Dolado;M. J. Stott;A. Ayuela
中科院分区：
文献类型：
--
作者：
Paweł Rejmak;J. Dolado;M. J. Stott;A. Ayuela
采用密度泛函理论计算了水泥基材料中硅原子的各向同性屏蔽，研究了水泥基材料中29Si的NMR谱。我们专注于水泥的主要成分，硅酸钙水合物凝胶，使用广泛接受的模型的基础上观察到的结构的jennite和雪硅钙石矿物。结果表明，29Si的化学位移不仅与通常认为的（SiO4）单元的凝聚程度有关，而且还与电荷补偿H和Ca阳离子的局部排列有关。我们发现，基于雪硅钙石的水化硅酸钙凝胶模型的核磁共振谱比基于尖晶石的模型更符合实验。
The NMR spectra of 29Si in cement-based materials are studied through calculations of the isotropic shielding of silicon atoms within the density functional theory. We focus on the main component of cement, the calcium-silicate-hydrate gel, using widely accepted models based on the observed structures of jennite and tobermorite minerals. The results show that the 29Si chemical shifts are dependent not only on the degree of condensation of the (SiO4) units, as commonly assumed, but also on the local arrangement of the charge compensating H and Ca cations. We find that the NMR spectra for models of the calcium-silicate-hydrate gel based on tobermorite are in better agreement with experiment than those for jennite-based models.