A potential C-S-H nucleation mechanism: atomistic simulations of the portlandite to C-S-H transformation

被引：24
作者：
Aretxabaleta X.M. [1 ]
López-Zorrilla J. [1 ]
Labbez C. [2 ]
Etxebarria I. [1 ,3 ]
Manzano H. [1 ]
机构：
[1] Fisika saila, Euskal Herriko Unibertsitatea UPV/EHU, Sarriena Auzoa z/g, Basque Country, Leioa
[2] ICB, UMR 6303 CNRS, Univ. Bourgogne Franche-Comté, Dijon
[3] EHU Quantum Center, Euskal Herriko Unibertsitatea, UPV/EHU
来源：
Cement and Concrete Research | 2022年 / 162卷
关键词：
Atomistic simulation; Calcium Silicate Hydrate; Free energy of reaction; Nucleation; Portlandite;
D O I：
10.1016/j.cemconres.2022.106965
中图分类号：
学科分类号：
摘要：
The nucleation of the C-S-H gel is a complex process, key to controlling the hydration kinetics and microstructure development of cement. In this paper, a mechanism for the crystallization step during the C-S-H gel non-classical nucleation is proposed and explored by atomistic simulation methods. In the proposed mechanism portlandite precursor monolayers undergo a chemically induced transformation by condensation of silicate dimmers, forming C-S-H monolayers. We studied by DFT and nudged elastic band the structural transformation from bulk portlandite to a tobermorite-like calcium hydroxide polymorph, and the silicate condensation reaction at portlandite surface. Then, both processes are studied together, investigating the topochemical transformation from a portlandite monolayer to a C-S-H monolayer at room conditions using targeted molecular dynamics and umbrella sampling methods. Comparing the free energy of the process with thermodynamic data we conclude that the proposed mechanism is a potential path for C-S-H formation. © 2022 The Author(s)
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