Electrostatic properties of C–S–H and C-A-S-H for predicting calcium and chloride adsorption

Yoshida, Shogo; Elakneswaran, Yogarajah; Nawa, Toyoharu

doi:10.1016/j.cemconcomp.2021.104109

Cited by 41 publications

(11 citation statements)

References 29 publications

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“…Transmission electron microscopy (TEM) images of C-S-H from samples of hydrated tricalcium silicate (C 3 S) , and TEM images of high Ca/Si pure phase synthetic C-S-H , show a nanofoil morphology, as seen in Figure . The nanofoils have a length around 100–200 nm ,− and a thickness below 5 nm. ,,, The measured specific surface area is in the range between 200 and 300 m 2 /g. − These observations underline the importance of C-S-H surfaces …”

Section: Introductionmentioning

confidence: 74%

“…The lower Ca/Si difference between the surface and bulk would make the Ca-Surface termination more likely than the Si-Surface 1 termination. However, Ca B fulfills the charge neutrality of the bridging site as well as the surface in general, which is contrary to the experimental observations which suggest high surface charge densities. ,,, Finally, due to the lack of surface silanol groups, the Si-OH/Si ratio of the bulk would be required to be 13%. Assuming again that silanol groups are preferentially found on Q 2b silicates, this would result in 41% of non-sharing bulk Q 2b oxygens to be protonated.…”

Section: Resultsmentioning

confidence: 99%

“…The newly proposed surface model can explain some previously unclear observations about zeta potentials. Viallis-Terrisse et al, Labbez et al, and Yoshida et al reported negative experimental values of zeta potential for C-S-H with Ca/Si of 0.66 and 1.34 in solutions with [Ca 2+ ] < 2 mM. As suggested by our model, the surface charge for Ca/Si < 1.4 is expected to be negative (charge in Figure ).…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Atomic-Level and Surface Structure of Calcium Silicate Hydrate Nanofoils

Casar,

Mohamed,

Bowen

et al. 2023

J. Phys. Chem. C

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Deciphering the calcium silicate hydrate (C-S-H) surface is crucial for unraveling the mechanisms of cement hydration and property development. Experimental observations of C-S-H in cement systems suggest a surface termination which is fundamentally different from the silicate-terminated surface assumed in many atomistic level studies. Here, a new multiparameter approach to describing the (001) basal C-S-H surface is developed, which considers how the surface termination affects the overall properties (Ca/Si ratio, mean chain length, relative concentration of silanol and hydroxide groups). Contrary to current beliefs, it is concluded that the (001) C-S-H surface is dominantly calcium terminated. Finally, an adsorption mechanism for calcium and hydroxide ions is proposed, which is in agreement with the surface charge densities observed in previous studies.

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Section: Introductionmentioning

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Atomic-Level and Surface Structure of Calcium Silicate Hydrate Nanofoils

Casar,

Mohamed,

Bowen

et al. 2023

J. Phys. Chem. C

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“…Although C-S-H bulk structure is well researched upon and understood, its surface is still somewhat of a mystery. It is known that C-S-H has a high specific surface area (between 200 and 300 m 2 /g [106]), which underlines the importance of C-S-H surface in the process of cement hydration [9] with many dynamic interactions of the dissolving ionic species. Such interactions dictate the cement or concrete microstructure development, thereby influencing the long-term durability and other properties of the concrete structure.…”

Section: C-s-h Interfacementioning

confidence: 99%

Molecular modelling of cementitious materials: current progress and benefits

et al. 2023

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Developing new sustainable concrete technology has become an urgent need, requiring faster and deeper insights into the fundamental mechanisms driving the cement hydration reactions. Molecular simulations have the potential to provide such understanding since the hydration reaction and the cement chemistry are particularly dominated by mechanisms at the atomic scale. In this letter, we review the application of two major approaches namely classical (including reactive) molecular dynamics simulations and density function theory calculations of cementitious materials. We give an overview of molecular simulations involving the major mineral and hydrate phases.

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“…However, Ref. [38] emphasizes on the subject the effect on the adsorption of aluminium's incorporation into C-S-H gel. The cation effect is as well addressed by [39] and they found that more chlorides were bound when the associated cation was Mg 2+ or Ca 2+ compared to Na + .…”

Section: Introductionmentioning

confidence: 99%

Finite Boundary Conditions Due to the Bar Presence in the Model of Chloride Penetration

Tavares

Andrade

2022

Materials

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The chloride penetration is usually modelled through the application of a solution of Fick’s second law of diffusion, based on the assumption of semi-infinite boundary conditions. However, the presence of the bars, on whose surface the chlorides accumulate, makes this assumption incorrect. As the time progresses, the chlorides in the steel/concrete interface increase in concentration more than the chlorides overpassing the bar position without obstacles. This circumstance, although previously studied, has not been introduced in common practice, in spite of it supposes early reaching of the chloride threshold. The study in this paper shows a deterministic analysis of the chloride diffusion process by the finite element method (FEM) which numerically solves Fick’s second law, taking into account the accumulation of the chlorides on the bar surface. Several examples are calculated and factors between the finite/semi-infinite solutions are given. These factors depend on the cover depth and the diffusion coefficient, and with less importance, on the diameter of the bar, which make it unfeasible to propose a general trend.

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Electrostatic properties of C–S–H and C-A-S-H for predicting calcium and chloride adsorption

Cited by 41 publications

References 29 publications

Atomic-Level and Surface Structure of Calcium Silicate Hydrate Nanofoils

Atomic-Level and Surface Structure of Calcium Silicate Hydrate Nanofoils

Molecular modelling of cementitious materials: current progress and benefits

Finite Boundary Conditions Due to the Bar Presence in the Model of Chloride Penetration

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