Correlation between Composition and Mechanical Properties of Calcium Silicate Hydrates Identified by Infrared Spectroscopy and Density Functional Theory
Correlation between Composition and Mechanical Properties of Calcium Silicate Hydrates Identified by Infrared Spectroscopy and Density Functional Theory
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DOI：
10.1021/acs.jpcc.8b11920
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发表时间：
2019-05-02
影响因子：
3.7
通讯作者：
Thissen, Peter
中科院分区：
文献类型：
--
作者：
Izadifar, Mohammadreza;Koeniger, Franz;Thissen, Peter
建筑和建造业是现代社会的支柱和推动力。今天，我们几乎所有的技术基础设施都是基于水泥基材料。在特高压条件下，在定义明确的矿物基质上的模型反应的详细光谱研究在很大程度上是缺乏的，从而禁止了理论方法的验证。即使是简单的化学过程也知之甚少。因此，防腐策略的合理设计几乎是不可能的。在这篇手稿中，我们研究了八种不同的硅酸钙（CS）或水合硅酸钙（CSH）相，即托贝莫来石14埃、托贝莫来石11埃、托贝莫来石9埃、钙硅石、霞石、霞石、γ-C2 S和α-C2 SH。这些代表性的模型相的密度泛函理论建模方法的帮助下计算。首先，我们关注材料的机械性能。我们的研究结果表明，jaffeite，γ-C2 S，和α-C2 SH具有线性体积模量，因为硅酸盐四面体的单体结构。雪硅钙石14埃和γ-C2 S分别表现出最低和最高的体积模量。在第二部分中，优化的几何形状允许通过力常数方法精确计算振动本征模式和频率。C/S和H/C的比例是我们模型体系中所有相的nu（Si-O）计算波数分类的主要标准。然而，γ-C2 S和α-C2 SH具有相等的C/S比。由于不同的H/C比，波数被发现为四个特征振动模式。α-C2 SH的C/S比与硫铁矿相比的贡献是对于具有相等H/C比的相要考虑的另一个方面。由于较低的C/S比，α-C2 SH表现出比jaffeite更高的波数。
Building and construction industries are at the same time the backbone and the driving force of our modern society. Nearly all our technical infrastructure today is based on cement-based materials. Detailed spectroscopic investigations of model reactions on well-defined mineral substrates under UHV conditions are largely lacking, thus prohibiting a validation of theoretical methods. Even simple chemical processes are poorly understood. As a result, the rational design of anticorrosion strategies is virtually impossible. In this manuscript, we have worked on eight different calcium-silicate (CS) or calcium-silicate-hydrate (CSH) phases, namely, tobermorite 14 angstrom, tobermorite 11 angstrom, tobermorite 9 angstrom, wollastonite, jaffeite, jennite, gamma-C2S, and alpha-C2SH. These representative model phases are calculated with the help of the density functional theory modeling method. Initially, we take care of the mechanical properties of the material. Our results revealed that jaffeite, gamma-C2S, and alpha-C2SH have a linear bulk modulus because of the monomer structure of silicate tetrahedra. Tobermorite 14 angstrom and gamma-C2S exhibit the lowest and highest bulk modulus, respectively. In the second part, the optimized geometries allow for the precise calculation of vibrational eigenmodes and frequencies by the force constant approach. The proportions of C/S and H/C are major criteria for the classification of the calculated wavenumber of nu(Si-O) for all phases in our model system. However, gamma-C2S and alpha-C2SH have an equal C/S ratio. As a result of the different H/C ratios, wavenumbers were found for four characteristic vibration modes. The contribution of the C/S ratio for alpha-C2SH in comparison to jaffeite is another aspect to be considered for phases with equal H/C ratios. Because of the lower C/S ratio, alpha-C2SH exhibits a higher wavenumber than jaffeite.