Effective Interactions between Calcium-Silicate-Hydrate Nanolayers
Effective Interactions between Calcium-Silicate-Hydrate Nanolayers
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DOI：
10.1021/acs.jpcc.8b08146
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发表时间：
2019-02-28
影响因子：
3.7
通讯作者：
Qomi, Mohammad Javad Abdolhosseini
中科院分区：
文献类型：
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作者：
Masoumi, Saeed;Zare, Siavash;Qomi, Mohammad Javad Abdolhosseini
水化硅酸钙（C-S-H）是水泥基材料中的主要粘结相，具有复杂的多尺度多孔结构，纳米级颗粒在其中有效地相互作用，对混凝土的宏观性能起着重要作用。因此，工程水泥材料的形态和性能可以通过以下方式获得：首先，研究可变化学组成对纳米级C-S-H纳米层的内聚力和性能的影响，然后，将这些信息转化为介观尺度，以便可以完成纹理分析。在这里，我们的目标是为这样一个全面的研究奠定基础。首先，我们构建可变的原子结构的C-S-H纳米层，并验证它们对实验测量。然后，我们进行自由能微扰分析，以测量具有不同化学组成的C-S-H纳米层之间的平均力势（PMF）。我们发现C-S-H的化学组成以及多晶型结构和测量PMFs的特性之间有很强的相关性。特别是，我们观察到的PMF形状从一个单一的最小值到多个最小值的过渡，表明亚稳态的出现在粒子间的相互作用。我们表明，通过PMF方法计算的C-S-H的关键力学性能与现有的实验数据是在一个合理的协议。所提出的PMFs可直接用于研究胶凝材料的结构属性以及水化过程的研究。
Calcium-silicate-hydrate (C-S-H), the main binding phase in cementitious materials, possesses a complex multiscale porous texture where nanosized particles interact effectively and contribute to the macroscopic properties of concrete. Engineering the morphology and properties of cementitious materials can thus be obtained by, first, studying the impact of the variable chemical composition on the cohesion and properties of nanolayers of C-S-H at the nanoscale arid, then, translating these information to the mesoscale so that a textural analysis can be accomplished. Here, we aim to establish a foundation for such a comprehensive study. First, we construct variable atomic structures of C-S-H nanolayers and validate them against experimental measurements. Then, we conduct free energy perturbation analysis to measure the potential-of-mean-force (PMF) between C-S-H nanolayers with varying chemical compositions. We find a strong correlation between the chemical composition as well as polymorphic structure of C-S-H and characteristics of measured PMFs. In particular, we observe a transition in PMF shape from a single minimum to multiple minima, indicating the emergence of metastable states in the interparticle interactions. We show that key mechanical properties of C-S-H calculated via the PMF approach are in a reasonable agreement with the available experimental data. The proposed PMFs can be directly used to investigate the textural attributes as well as the study of the hydration process in cementitious materials.