Toward a better comprehension and modeling of hysteresis cycles in the water sorption–desorption process for cement based materials

Ranaivomanana, Harifidy; Verdier, Jérôme; Sellier, Alain; Bourbon, Xavier

doi:10.1016/j.cemconres.2011.03.012

Cited by 79 publications

(73 citation statements)

References 43 publications

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“…15. It is worth pointing out that the experimental data given in [38] were collected from [11,[39][40][41][42]. The simulation results show a general satisfactory agreement with the experimental data.…”

Section: D Equilibrium Distribution Of Water and Gas Phasessupporting

confidence: 63%

Pore-scale modelling of relative permeability of cementitious materials using X-ray computed microtomography images

Zhang

2017

Cement and Concrete Research

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Permeability of cementitious materials is an important durability indicator. In practice, concrete is rarely saturated. Therefore, it is essential to study permeability of unsaturated cementitious materials. This paper presents an integrated modelling approach for estimating permeability of cementitious materials over the full range of saturation. An in-house code based on multiphase and single-phase lattice Boltzmann models is developed and used to simulate the moisture distribution and fluid flow in unsaturated cement paste with various curing ages, the 3D microstructures of which are obtained from X-ray micro-CT. The water permeability and gas permeability of partially saturated cement paste are then estimated. The results indicate with decreasing water saturation water permeability decreases while gas permeability increases. Additionally, the moisture distribution and permeability of unsaturated cement paste are strongly dependent on its microstructure. Moreover, there exists a unique relationship between permeability and effective porosity. The simulation results show good agreement with experimental data.

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Section: D Equilibrium Distribution Of Water and Gas Phasessupporting

confidence: 63%

Pore-scale modelling of relative permeability of cementitious materials using X-ray computed microtomography images

Zhang

2017

Cement and Concrete Research

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“…The water sorption isotherm [water content as a function of relative humidity (RH) during drying and rewetting] is potentially a powerful technique to understand changes in this microstructure, as it samples evaporable water at all scales [17][18][19]. Even more information is obtained by also measuring the bulk-volume change with RH.…”

Section: Introductionmentioning

confidence: 99%

“…At present, connections between measured sorption isotherms, pore structure, and associated properties rely on models that link the evaporation and condensation of water at a given RH with the width and connectedness of the pores over a range of scales [18,19,21,22]. Models for mesoporous materials are typically extensions of the Kelvin-Laplace theory, which links the RH with the width of pores being emptied or filled and with the pore pressure causing volumetric strain [23,24].…”

Section: Introductionmentioning

confidence: 99%

Hysteresis from Multiscale Porosity: Modeling Water Sorption and Shrinkage in Cement Paste

et al. 2015

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Cement paste has a complex distribution of pores and molecular-scale spaces. This distribution controls the hysteresis of water sorption isotherms and associated bulk dimensional changes (shrinkage). We focus on two locations of evaporable water within the fine structure of pastes, each having unique properties, and we present applied physics models that capture the hysteresis by dividing drying and rewetting into two related regimes based on relative humidity (RH). We show that a continuum model, incorporating a poreblocking mechanism for desorption and equilibrium thermodynamics for adsorption, explains well the sorption hysteresis for a paste that remains above approximately 20% RH. In addition, we show with molecular models and experiments that water in spaces of ≲1 nm width evaporates below approximately 20% RH but reenters throughout the entire RH range. This water is responsible for a drying shrinkage hysteresis similar to that of clays but opposite in direction to typical mesoporous glass. Combining the models of these two regimes allows the entire drying and rewetting hysteresis to be reproduced accurately and provides parameters to predict the corresponding dimensional changes. The resulting model can improve the engineering predictions of long-term drying shrinkage accounting also for the history dependence of strain induced by hysteresis. Alternative strategies for quantitative analyses of the * Corresponding author. hmj@mit.edu PHYSICAL REVIEW APPLIED 3, 064009 (2015) 2331-7019=15=3(6)=064009 (17) 064009-1

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“…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)(5)(6)(7)(8). 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.

207

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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Toward a better comprehension and modeling of hysteresis cycles in the water sorption–desorption process for cement based materials

Cited by 79 publications

References 43 publications

Pore-scale modelling of relative permeability of cementitious materials using X-ray computed microtomography images

Pore-scale modelling of relative permeability of cementitious materials using X-ray computed microtomography images

Hysteresis from Multiscale Porosity: Modeling Water Sorption and Shrinkage in Cement Paste

Mesoscale texture of cement hydrates

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