Effective Interactions between Calcium-Silicate-Hydrate Nanolayers

Masoumi, Saeed; Zare, Siavash; Valipour, Hamid; Qomi, Mohammad Javad Abdolhosseini

doi:10.1021/acs.jpcc.8b08146

Cited by 61 publications

(72 citation statements)

References 77 publications

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“…When comparing our results with those of Ebrahimi et al, we find that C–S–H and clay clusters have distinct mechanophysical properties due to the sheer difference in the strength of ionic correlation forces in each system. As noted recently by Masoumi et al, the charge‐per‐surface area controls the characteristics of ionic correlation forces between C–S–H layers. The surface charge density in the C–S–H is much greater than that in clay minerals.…”

Section: Discussion On Model Parameter Uncertainties and Sensitivitiesmentioning

confidence: 81%

“…We add/remove extra oxygen atoms at the supercell boundaries to make sure silica tetrahedra is fully formed. As suggested by the reactive force field simulations, we protonate ending oxygen atoms to balance the local charge of ending sites. To set up the interlayer ionic content, we use the inelastic neutron scattering measurement, that is, CaOH/S ~0.76 corresponding to PH >12 .…”

Section: The Effective Interaction Between C–s–h Nanolayersmentioning

confidence: 99%

“…As a result of strong ionic correlation forces, 41,42,57,92 C-S-H nanolayers adhere strongly together and form colloidal nanosized clusters. 79,93 Due to the absence of foreign surface for heterogeneous nucleation of C-S-H layers in our simulations, the texture of our mesoscale models resembles those of inner products, and it is distinct from that of fibrillar outer products that precipitate on the surface of cement clinkers.…”

Section: C-s-h Gelmentioning

confidence: 99%

“…The distribution skews toward denser local packing densities as a result of an increase in overall packing fraction [Color figure can be viewed at wileyonlinelibrary.com] simulations. 41,42,57 These MPFs are dominated by layers' face-to-face interactions as a result of attractive ionic correlation effects that cannot be described via the mean-field theories such as the celebrated DLVO theory. The features of these free energy curves in the face-to-face direction govern the behaviors of the gel at the mesoscale.…”

Section: Parameter Uncertainties and Sensitivitiesmentioning

confidence: 99%

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Nanolayered attributes of calcium‐silicate‐hydrate gels

et al. 2019

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Calcium‐silicate‐hydrates (C–S–H) gel, the main binding phase in cementitious materials, has a complex multiscale texture. Despite decades of intensive research, the relation between C–S–H's chemical composition and mesoscale texture remains experimentally limited to probe and theoretically elusive to comprehend. While the nanogranular texture explains a wide range of experimental observations, understanding the fundamental processes that control particles’ size and shape are still obscure. This paper strives to establish a link between the chemistry of C–S–H nanolayers at the molecular level and formation of C–S–H globules at the mesoscale via the potential‐of‐mean‐force (PMF) coarse‐graining approach. We propose a new thermomechanical load‐cycling scheme that effectively packs polydisperse coarse‐grained nanolayers and creates representative C–S–H gel structures at various packing densities. We find that the C–S–H nanolayers percolate at ~10% packing fraction, significantly below the percolation of ideal hard contact oblate particles and rather close to that of overlapping ellipsoids. The agglomeration of C–S–H nanolayers leads to the formation of globular clusters with the effective thickness of ~5 nm, in striking agreement with small angle neutron and X‐ray scattering measurements as well as nanoscale imaging observations. The study of pore structure and local packing distribution in the course of densification shows a transition from a connected pore network to isolated nanoporosity. Furthermore, the calculated mechanical properties are in excellent agreement with statistical nanoindentation experiments, positioning nanolayered morphology as a finer description of C–S–H globule models. Such high‐resolution description becomes indispensable when investigating phenomena that involve internal building blocks of globules such as shrinkage and creep.

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Section: Discussion On Model Parameter Uncertainties and Sensitivitiesmentioning

confidence: 81%

Section: The Effective Interaction Between C–s–h Nanolayersmentioning

confidence: 99%

Section: C-s-h Gelmentioning

confidence: 99%

Section: Parameter Uncertainties and Sensitivitiesmentioning

confidence: 99%

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Nanolayered attributes of calcium‐silicate‐hydrate gels

et al. 2019

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“…on August 8, 2021 http://advances.sciencemag.org/ Downloaded from (19,21,23,24,30,(45)(46)(47)(48)(49). By the end of hydration, C-S-H becomes denser and denser, and its nanoscale features (including the interlayer distances and chemical compositions usually described in terms of Ca/Si ratio) play a predominant role in most observations and studies (16,21,29). Nevertheless, the earlier-stage mesoscale morphology controls the development of larger pores and contributes to local stresses in the initial gel network, which have consequences for the long-term evolution of the material and its interactions with the environment (5,43,44,(50)(51)(52)(53).…”

Section: Discussionmentioning

confidence: 99%

The physics of cement cohesion

et al. 2021

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Cement is the most produced material in the world. A major player in greenhouse gas emissions, it is the main binding agent in concrete, providing a cohesive strength that rapidly increases during setting. Understanding how such cohesion emerges is a major obstacle to advances in cement science and technology. Here, we combine computational statistical mechanics and theory to demonstrate how cement cohesion arises from the organization of interlocked ions and water, progressively confined in nanoslits between charged surfaces of calcium-silicate-hydrates. Because of the water/ions interlocking, dielectric screening is drastically reduced and ionic correlations are proven notably stronger than previously thought, dictating the evolution of nanoscale interactions during cement hydration. By developing a quantitative analytical prediction of cement cohesion based on Coulombic forces, we reconcile a fundamental understanding of cement hydration with the fully atomistic description of the solid cement paste and open new paths for scientific design of construction materials.

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