Time dependent driving forces and the kinetics of tricalcium silicate hydration
Time dependent driving forces and the kinetics of tricalcium silicate hydration
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DOI：
10.1016/j.cemconres.2015.03.016
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发表时间：
2015-08-01
影响因子：
11.4
通讯作者：
Thomas, Jeffrey J.
中科院分区：
文献类型：
--
作者：
Bullard, Jeffrey W.;Scherer, George W.;Thomas, Jeffrey J.
使用动力学元胞自动机程序HydratiCA模拟硅酸三钙（C3 S）水化表明，净速率取决于C3 S溶解和水化产物生长。这两种方法都不能被认为是唯一的速率控制步骤，因为溶液相对于C3 S保持显著欠饱和，而相对于硅酸钙水合物（C-S-H）保持显著过饱和。反应速率峰的出现是由于C-S-H对C_3S的覆盖度增加，降低了C-S-H的溶解速率和过饱和度。这种过饱和依赖性被包括在一个广义的边界成核和生长模型来描述的动力学，而不需要单独的水泥颗粒上的产品的显着的冲击。后一点解释了浆体水化速率对水/水泥比不敏感的观察结果。模拟表明，C3 S上的产品层仍然是可渗透的，没有过渡到扩散控制的指示，即使长时间后的速率峰值。出版社：Elsevier Ltd
Simulations of tricalcium silicate (C3S) hydration using a kinetic cellular automaton program, HydratiCA, indicate that the net rate depends both on C3S dissolution and on hydration product growth. Neither process can be considered the sole rate-controlling step because the solution remains significantly undersaturated with respect to C3S yet significantly supersaturated with respect to calcium silicate hydrate (C-S-H). The reaction rate peak is attributed to increasing coverage of C3S by C-S-H, which reduces both the dissolution rate and the supersaturadon of C-S-H. This supersaturation dependence is included in a generalized boundary nucleation and growth model to describe the kinetics without requiring significant impingement of products on separate cement grains. The latter point explains the observation that paste hydration rates are insensitive to water/cement ratio. The simulations indicate that the product layer on C3S remains permeable; no transition to diffusion control is indicated, even long after the rate peak. Published by Elsevier Ltd.