Analysis of C–S–H gel and cement paste by small-angle neutron scattering

Allen, Andrew J.; Thomas, Jeffrey J.

doi:10.1016/j.cemconres.2006.09.002

Cited by 114 publications

(44 citation statements)

References 27 publications

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“…Our simulations predict 190 m 2 /g for the globules and values of ~100 m 2 /g and 65 m 2 /g for the LD and HD structures respectively. It is remarkable that the SSAs of our globules match reasonably well with the SSAs experimentally observed by neutrons ~ (225 m 2 /gCSH) (24)(25)(26). In the case of CM-I the SSAs measured by SANS were explained by assuming that the globules belonging to the HD structures are invisible to the neutrons.…”

Section: Surface Areassupporting

confidence: 74%

“…Nuestras simulaciones predicen valores de 190 m 2 /g para los glóbulos y valores de ~100 m 2 /g y ~65 m 2 /g para las estructuras de LD y HD, respectivamente. Es reseñable el hecho de que las superficies específicas de nuestros glóbulos coincidan razonablemente con las obtenidas experimentalmente mediante neutrones ~225 m 2 /g C-S-H (24)(25)(26). En el caso del CM-I las superficies específicas medidas mediante SANS fueron explicadas asumiendo que los glóbulos pertenecientes a las estructuras HD son invisibles a los neutrones.…”

Section: Surface Areasunclassified

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Modelos estructurales del empaquetamiento aleatorio de partículas esféricas de Tobermorita: una aproximación computacional sencilla

González-Teresa¹,

Morales‐Flórez²,

Manzano³

et al. 2010

Mater. construcc.

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RESUMENEn este trabajo y con el objetivo de conjugar el punto de vista atomístico y coloidal, presentamos un método computacional Monte Carlo que reproduce el empaquetamiento coloidal de nano-partículas esféricas cristalinas de tipo Tobermorita. Variando los parámetros computacionales de empaquetamiento diferentes estructuras tipo Low Density (LD) C-S-H y High Density (HD) C-S-H han sido creadas. Posteriormente, las estructuras resultantes de nuestros experimentos computacionales han sido analizadas en términos de sus densidades, áreas especí-ficas y propiedades mecánicas.Palabras clave: gel C-S-H, modelo coloidal, simulación computacional. SUMMARYIn this work, and in order to bring together the atomistic and colloidal viewpoints, we will present a Monte Carlo computational scheme which reproduces the colloidal packing of nano-spherical crystalline tobermorite-like particles. Different Low Density (LD) C-S-H and High Density (HD) C-S-H structures will be developed just by varying the computational packing parameters. Finally, the structures resulting from our computational experiments will be analyzed in terms of their densities, surface areas and their mechanical properties.K Ke ey yw wo or rd ds s: : C-S-H gel, colloidal model, modelling.

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Section: Surface Areassupporting

confidence: 74%

Section: Surface Areasunclassified

Modelos estructurales del empaquetamiento aleatorio de partículas esféricas de Tobermorita: una aproximación computacional sencilla

González-Teresa¹,

Morales‐Flórez²,

Manzano³

et al. 2010

Mater. construcc.

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“…This trend is more pronounced with increasing overall packing fraction. The structures from the simulations can be compared with small-angle X-ray scattering (SAXS) or SANS data, which are extensively used to characterize and infer texture properties of hardened cement pastes (4,14,17,(25)(26)(27). In Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The hygrothermal behavior of cement suggests a hierarchical and complex pore structure that develops during hydration and continues to evolve (1,(9)(10)(11). NMR and small-angle neutron scattering (SANS) studies of hardened C-S-H identified distinctive features of the complex pore network and detected significant structural heterogeneities spanning length scales between tens and hundreds of nanometers (12)(13)(14).…”

mentioning

confidence: 99%

Mesoscale texture of cement hydrates

Ioannidou

Krakowiak

Bauchy

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

199

146

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Strength and other mechanical properties of cement and concrete rely upon the formation of calcium-silicate-hydrates (C-S-H) during cement hydration. Controlling structure and properties of the C-S-H phase is a challenge, due to the complexity of this hydration product and of the mechanisms that drive its precipitation from the ionic solution upon dissolution of cement grains in water.Departing from traditional models mostly focused on length scales above the micrometer, recent research addressed the molecular structure of C-S-H. However, small-angle neutron scattering, electron-microscopy imaging, and nanoindentation experiments suggest that its mesoscale organization, extending over hundreds of nanometers, may be more important. Here we unveil the C-S-H mesoscale texture, a crucial step to connect the fundamental scales to the macroscale of engineering properties. We use simulations that combine information of the nanoscale building units of C-S-H and their effective interactions, obtained from atomistic simulations and experiments, into a statistical physics framework for aggregating nanoparticles. We compute small-angle scattering intensities, pore size distributions, specific surface area, local densities, indentation modulus, and hardness of the material, providing quantitative understanding of different experimental investigations. Our results provide insight into how the heterogeneities developed during the early stages of hydration persist in the structure of C-S-H and impact the mechanical performance of the hardened cement paste. Unraveling such links in cement hydrates can be groundbreaking and controlling them can be the key to smarter mix designs of cementitious materials.U pon dissolution of cement powder in water, calcium-silicate-hydrates (C-S-H) precipitate and assemble into a cohesive gel that fills the pore space in the cement paste over hundreds of nanometers and binds the different components of concrete together (1). The mechanics and microstructure are key to concrete performance and durability, but the level of understanding needed to design new, more performant cements and have an impact on the CO 2 footprint of the material is far from being reached (2).Most of the experimental characterization and models used to predict and design cement performance have been developed at a macroscopic level and hardly include any material heterogeneity over length scales smaller than micrometers (3). However, EM imaging, nanoindentation tests, X-rays and neutron scattering, and NMR analysis as well as atomistic simulations have now elucidated several structural and mechanical features concentrated within a few nanometers (4-8). The hygrothermal behavior of cement suggests a hierarchical and complex pore structure that develops during hydration and continues to evolve (1, 9-11). NMR and small-angle neutron scattering (SANS) studies of hardened C-S-H identified distinctive features of the complex pore network and detected significant structural heterogeneities spanning length scales between tens and hu...

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“…It is also successfully used to study at the nanoscale a variety of nanodispersed materials and to determine structural parameters of nanomaterials, as well as bulk ones containing nanodispersed components, e.g. hydrated cement compositions [14][15][16].…”

Section: Methodsmentioning

confidence: 99%

Technogenic resources for nanotechnologies in construction

2017

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Abstract.A large group of industrial wastes from water purification, treatment and softening has been considered. The reference is made to the fact that slurries are a unique man-made product technologically ready for use and constantly restocking. Slurries have been classified by conditions of the formation, composition, chemical and physical properties. The nanoscale structural parameters of the slurry particles (the size distribution and fractal dimension) have been determined by the neutron small-angle scattering method. The conducted researches allow slurries to be considered a nanotechnogenic raw material. The use of slurries as additives in the building material production process reduces the harmful influence of industrial wastes on the environment and creates a significant reserve of material and energy resources in the construction industry.

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Analysis of C–S–H gel and cement paste by small-angle neutron scattering

Cited by 114 publications

References 27 publications

Modelos estructurales del empaquetamiento aleatorio de partículas esféricas de Tobermorita: una aproximación computacional sencilla

Modelos estructurales del empaquetamiento aleatorio de partículas esféricas de Tobermorita: una aproximación computacional sencilla

Mesoscale texture of cement hydrates

Technogenic resources for nanotechnologies in construction

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