Is cement a glassy material?

Bauchy, Mathieu; Qomi, Mohammad Javad Abdolhosseini; Ulm, Franz Josef; Pellenq, Roland

doi:10.1201/b16645-19

Cited by 10 publications

(4 citation statements)

References 21 publications

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“…The computed amount of adsorbed water is in excellent agreement with experimental data, which reflects the relevance of the present approach in describing CSH [41]. The ReaxFF potential [45], a reactive potential, is finally used to account for the reaction of the interlayer water with the defective calcium-silicate sheets, thereby creating hydroxyl groups [46]. The details of the simulations of the CSH samples, as well as their hardness computation, can be found in Supplementary Note 1 and 3 and Ref.…”

Section: Methodssupporting

confidence: 64%

Fracture toughness anomalies: Viewpoint of topological constraint theory

Bauchy

Wang

et al. 2016

Acta Materialia

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International audienceThe relationship between composition, structure, and resistance to fracture remains poorly understood. Here, based on molecular dynamics simulations, we report that sodium silicate glasses and calcium silicate hydrates feature an anomalous maximum in fracture toughness. In the framework of topological constraint theory, this anomaly is correlated to a flexible-to-rigid transition, driven by pressure or composition for sodium silicate and calcium silicate hydrates, respectively. This topological transition, observed for an isostatic network, is also shown to correspond to a ductile-to-brittle transition. At this state, the network is rigid but free of eigen-stress and features stress relaxation through crack blunting, resulting in optimal resistance to fracture. Our topological approach could therefore enable the computational design of tough inorganic solids, which has long been a ``holy grail'' within the nonmetallic materials chemistry community. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

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Section: Methodssupporting

confidence: 64%

Fracture toughness anomalies: Viewpoint of topological constraint theory

Bauchy

Wang

et al. 2016

Acta Materialia

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“…Although the system is globally disordered, a direct observation of the atomic configuration (see Figure ) reveals that it maintains the layered structure characteristic of the tobermorite crystal. ,,, This can be problematic for the enumeration of the constraints since, in crystals, some apparently intact constraints can, in fact, be mutually dependent, thus leading to an overestimation of the number of constraints. In addition, the existence of such layers means that the system is not homogeneous.…”

Section: Numerical Detailsmentioning

confidence: 99%

Nanoscale Structure of Cement: Viewpoint of Rigidity Theory

et al. 2014

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Rigidity theory is a powerful tool to predict the properties of glasses with respect to composition. By reducing such molecular networks to simple mechanical trusses, topological constraint theory filters out all the unnecessary details that ultimately do not affect macroscopic properties. However, the usual constraint enumeration is restricted to networks that are amorphous, homogeneous, and fully connected. On the contrary, calcium−silicate−hydrate (C− S−H), the binding phase of cement, is partially crystalline and heterogeneous and shows some isolated water molecules. Here, we report how rigidity theory can be used to describe the nanoscale structure of this material by relying on molecular dynamics simulations. The distinction between intact and broken constraints is clearly defined at the atomic scale, thus allowing a precise enumeration of the topological constraints. We show that the rigidity of the C−S−H network can be increased by decreasing the Ca/Si molar ratio, which, as predicted by rigidity theory, allows improvement of the hardness of the material. This study suggests that rigidity theory could be applied with great rewards to a broader range of materials than glasses.

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“…Hardness of various oxide and chalcogenide phases as a function of their number of angular BB constraints per atom[11,31,96,[105][106][107][108][109][110][111][112][113][114][115].…”

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confidence: 99%

Topological Constraint Theory and Rigidity of Glasses

Bauchy¹

2019

21st Century Nanoscience – A Handbook

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Topological constraint theory has become an increasingly popular tool to predict the compositional dependence of glass properties or pinpoint promising compositions with tailored functionalities. This approach reduces complex disordered networks into simpler mechanical trusses. Thereby, topological constraint theory captures the important atomic topology that controls macroscopic properties while filtering out less relevant second-order structural details. As such, topological constraint theory can be used to decode the genome of glass, that is, to identify and decipher how the basic structural building blocks of glasses control their engineering properties-in the same way as the human genome offers information that serves as a blueprint for an individual's growth and development. Thanks to its elegance and simplicity, topological constraint theory has enabled the development of various physics-based models that can analytically predict various properties of glass. In this Chapter, I introduce some general background in glass science, concepts of atomic rigidity, and topological constraint theory. The topological constraints enumeration scheme is presented for various archetypical glasses and is used to understand the origin of their glass-forming ability. Finally, various topological models enabling the prediction of glass properties are reviewed, with a focus on hardness, fracture toughness, viscosity, fragility, glass transition temperature, and dissolution kinetics. Time Scientific progress Fig. 1: The discovery of new materials largely defines the progress of our civilization. Glass genome and discovery of new compositionsRevealing the full potential of glass requires the discovery of new glass formulations showing unique properties. However, this task is especially complicated for non-crystalline glassy materials for several reasons. First, virtually all the elements of the periodic table can be turned into a glass, if cooled fast enough from the liquid state [9]. Second, unlike crystals, glasses do not have to satisfy any fixed stoichiometry thanks to their out-of-equilibrium nature. As such, the composition of glasses can be continuously changed. For all these reasons, the number of possible glass compositions has been estimated to be around 1052! Yet, only about 200,000 glass compositions have been produced in the last 6000 years of human glass history [9]. These numbers demonstrate that the range of possible glasses remains largely unexplored-so that there exists an incredible opportunity for the future discovery of new glass formulations with unusual functionalities.However, although it offers a large room for improvement, the astronomical number of possible glass compositions is also a challenge. Indeed, such a large parametric space renders traditional Edisonian discovery approach based on trial-and-error largely inefficient. To accelerate the discovery of new glass formulations, it is necessary to decode the Glass Genome, that is, to decipher how the properties of glasses are controlled by their und...

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Is cement a glassy material?

Cited by 10 publications

References 21 publications

Fracture toughness anomalies: Viewpoint of topological constraint theory

Fracture toughness anomalies: Viewpoint of topological constraint theory

Nanoscale Structure of Cement: Viewpoint of Rigidity Theory

Topological Constraint Theory and Rigidity of Glasses

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