Elucidating the Effect of Water-To-Cement Ratio on the Hydration Mechanisms of Cement
Elucidating the Effect of Water-To-Cement Ratio on the Hydration Mechanisms of Cement
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DOI：
10.1021/acsomega.8b00097
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发表时间：
2018-05-01
期刊：
影响因子：
4.1
通讯作者：
Feys, Dimitri
中科院分区：
文献类型：
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作者：
Ley-Hernandez, Aida Margarita;Lapeyre, Jonathan;Feys, Dimitri
水泥的水化过程通常被模拟为相边界成核和生长（pBNG）过程。经典的pBNG模型，基于使用的各向同性和恒定的增长率的主要水合物，即，硅酸钙水合物（C-S-H），是无法解释缺乏任何显着的影响，水灰比（w/c）的水泥水化动力学。本文提出了pBNG模型的一种修正形式，其中C-S-H的各向异性生长可以随其在溶液中过饱和度的非线性演化而变化。结果表明，一旦超临界C-SH核的形成，它们的生长保持限制在一个区域内接近水泥颗粒。这被假设为水泥颗粒沉降的表现，其对C-S-H生长施加空间约束。在水泥颗粒的沉降被破坏的浆体中，水化动力学不再对w/c的变化不敏感。与C-S-H不同，溶液中的离子不受限制，因此，C-S-H的过饱和依赖生长速率随着w/c的增加而单调减小。总体而言，这项工作的成果突出了在采用pBNG模型模拟水泥基系统的水化作用时需要考虑的重要方面。
The hydration of cement is often modeled as a phase boundary nucleation and growth (pBNG) process. Classical pBNG models, based on the use of isotropic and constant growth rate of the main hydrate, that is, calcium-silicate-hydrate (C-S-H), are unable to explain the lack of any significant effect of the water-to-cement (w/c) ratio on the hydration kinetics of cement. This paper presents a modified form of the pBNG model, in which the anisotropic growth of C-S-H is allowed to vary in relation to the nonlinear evolution of its supersaturation in solution. Results show that once the supercritical C-SH nuclei form, their growth remains confined within a region in proximity to the cement particles. This is hypothesized to be a manifestation of the sedimentation of cement particles, which imposes a space constraint for C-S-H growth. In pastes wherein the sedimentation of cement particles is disrupted, the hydration kinetics are no longer unresponsive to changes in w/c. Unlike C-S-H, the ions in solution are not confined, and hence, the supersaturation-dependent growth rate of C-S-H diminishes monotonically with increasing w/c. Overall, the outcomes of this work highlight important aspects that need to be considered in employing pBNG models for simulating hydration of cement-based systems.