Ab initio metadynamics simulations on the formation of calcium silicate aqua complexes prior to the nuleation of calcium silicate hydrate

Yunjian Li; Hui Pan; Zongjin Li

doi:10.1016/j.cemconres.2022.106767

Ab initio metadynamics simulations on the formation of calcium silicate aqua complexes prior to the nuleation of calcium silicate hydrate

Yunjian Li
, Hui Pan
, Zongjin Li^*

^*Corresponding author for this work

Research output: Contribution to journal › Journal Article › peer-review

38 Citations (Scopus)

Abstract

Although the calcium silicate hydrate (C-S-H) has been used for millennium, the structure and formation of C-S-H are still unclear at atomistic level. In this work, we find two kinds of calcium silicate aqua complexes, [Ca(H₂O)_n(SiO₂(OH)₂)] and [Ca(H₂O)_n(SiO(OH)₃)]⁺, prior to the nuleation of C-S-H. The ab initio metadynamics simulations show that [Ca(H₂O)_n(SiO₂(OH)₂)] and [Ca(H₂O)_n(SiO(OH)₃)]⁺ have six and five stable states on the free energy surface (FES), respectively. There are different ligand substitution mechanisms between the FES minima. The four- and six- coordinated [Ca(H₂O)_n(SiO₂(OH)₂)] only follow associative and dissociative mechanisms, respectively. While both dissociative and associative mechanisms apply to the six-coordinated [Ca(H₂O)_n(SiO(OH)₃)]⁺ and no four-coordinated ligand substitution reaction is found. The most stable states in both systems show a distorted Ca[sbnd]O octahedral feature. Our findings may promote a fundamental understanding for the calcium silicate based species in solution and pre-nucleation process of C-S-H.

Original language	English
Article number	106767
Number of pages	12
Journal	Cement and Concrete Research
Volume	156
Early online date	12 Mar 2022
DOIs	https://doi.org/10.1016/j.cemconres.2022.106767
Publication status	Published - Jun 2022
Externally published	Yes

Bibliographical note

Publisher Copyright:
© 2022 Elsevier Ltd

Keywords

Calcium silicate hydrate (C-S-H)
Hydration
Ab initio metadynamics simulations
Ligand substitution mechanisms
Pre-nucleation

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10.1016/j.cemconres.2022.106767

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title = "Ab initio metadynamics simulations on the formation of calcium silicate aqua complexes prior to the nuleation of calcium silicate hydrate",

abstract = "Although the calcium silicate hydrate (C-S-H) has been used for millennium, the structure and formation of C-S-H are still unclear at atomistic level. In this work, we find two kinds of calcium silicate aqua complexes, [Ca(H2O)n(SiO2(OH)2)] and [Ca(H2O)n(SiO(OH)3)]+, prior to the nuleation of C-S-H. The ab initio metadynamics simulations show that [Ca(H2O)n(SiO2(OH)2)] and [Ca(H2O)n(SiO(OH)3)]+ have six and five stable states on the free energy surface (FES), respectively. There are different ligand substitution mechanisms between the FES minima. The four- and six- coordinated [Ca(H2O)n(SiO2(OH)2)] only follow associative and dissociative mechanisms, respectively. While both dissociative and associative mechanisms apply to the six-coordinated [Ca(H2O)n(SiO(OH)3)]+ and no four-coordinated ligand substitution reaction is found. The most stable states in both systems show a distorted Ca[sbnd]O octahedral feature. Our findings may promote a fundamental understanding for the calcium silicate based species in solution and pre-nucleation process of C-S-H.",

keywords = "Calcium silicate hydrate (C-S-H), Hydration, Ab initio metadynamics simulations, Ligand substitution mechanisms, Pre-nucleation",

author = "Yunjian Li and Hui Pan and Zongjin Li",

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year = "2022",

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language = "English",

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TY - JOUR

T1 - Ab initio metadynamics simulations on the formation of calcium silicate aqua complexes prior to the nuleation of calcium silicate hydrate

AU - Li, Yunjian

AU - Pan, Hui

AU - Li, Zongjin

PY - 2022/6

Y1 - 2022/6

N2 - Although the calcium silicate hydrate (C-S-H) has been used for millennium, the structure and formation of C-S-H are still unclear at atomistic level. In this work, we find two kinds of calcium silicate aqua complexes, [Ca(H2O)n(SiO2(OH)2)] and [Ca(H2O)n(SiO(OH)3)]+, prior to the nuleation of C-S-H. The ab initio metadynamics simulations show that [Ca(H2O)n(SiO2(OH)2)] and [Ca(H2O)n(SiO(OH)3)]+ have six and five stable states on the free energy surface (FES), respectively. There are different ligand substitution mechanisms between the FES minima. The four- and six- coordinated [Ca(H2O)n(SiO2(OH)2)] only follow associative and dissociative mechanisms, respectively. While both dissociative and associative mechanisms apply to the six-coordinated [Ca(H2O)n(SiO(OH)3)]+ and no four-coordinated ligand substitution reaction is found. The most stable states in both systems show a distorted Ca[sbnd]O octahedral feature. Our findings may promote a fundamental understanding for the calcium silicate based species in solution and pre-nucleation process of C-S-H.

AB - Although the calcium silicate hydrate (C-S-H) has been used for millennium, the structure and formation of C-S-H are still unclear at atomistic level. In this work, we find two kinds of calcium silicate aqua complexes, [Ca(H2O)n(SiO2(OH)2)] and [Ca(H2O)n(SiO(OH)3)]+, prior to the nuleation of C-S-H. The ab initio metadynamics simulations show that [Ca(H2O)n(SiO2(OH)2)] and [Ca(H2O)n(SiO(OH)3)]+ have six and five stable states on the free energy surface (FES), respectively. There are different ligand substitution mechanisms between the FES minima. The four- and six- coordinated [Ca(H2O)n(SiO2(OH)2)] only follow associative and dissociative mechanisms, respectively. While both dissociative and associative mechanisms apply to the six-coordinated [Ca(H2O)n(SiO(OH)3)]+ and no four-coordinated ligand substitution reaction is found. The most stable states in both systems show a distorted Ca[sbnd]O octahedral feature. Our findings may promote a fundamental understanding for the calcium silicate based species in solution and pre-nucleation process of C-S-H.

KW - Calcium silicate hydrate (C-S-H)

KW - Hydration

KW - Ab initio metadynamics simulations

KW - Ligand substitution mechanisms

KW - Pre-nucleation

UR - https://www.webofscience.com/wos/woscc/full-record/WOS:000860772400002

UR - https://www.scopus.com/pages/publications/85126115816

U2 - 10.1016/j.cemconres.2022.106767

DO - 10.1016/j.cemconres.2022.106767

M3 - Journal Article

AN - SCOPUS:85126115816

SN - 0008-8846

VL - 156

JO - Cement and Concrete Research

JF - Cement and Concrete Research

M1 - 106767

ER -

Ab initio metadynamics simulations on the formation of calcium silicate aqua complexes prior to the nuleation of calcium silicate hydrate

Abstract

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Keywords

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