Inferring pore connectivity from sorption hysteresis in multiscale porous media

Pinson, Matthew B.; Zhou, Tianci; Jennings, Hamlin M.; Bazant, Martin Z.

doi:10.1016/j.jcis.2018.07.095

Cited by 47 publications

(57 citation statements)

References 87 publications

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“…Our approach allows us to explain the water hysteresis loop from metastable ink bottleneck states on desorption due to the pore constrictions in cement paste. This contrasts with previous results based on equilibrium thermodynamics for both adsorption and desorption branches and pore connectivity assumption (23, 24).…”

Section: Sorption Hysteresis and Pore Size Distributionscontrasting

confidence: 99%

Multiscale poromechanics of wet cement paste

Zhou

Ioannidou

Ulm

et al. 2019

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

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Capillary effects, such as imbibition drying cycles, impact the mechanics of granular systems over time. A multiscale poromechanics framework was applied to cement paste, which is the most common building material, experiencing broad humidity variations over the lifetime of infrastructure. First, the liquid density distribution at intermediate to high relative humidity is obtained using a lattice gas density functional method together with a realistic nanogranular model of cement hydrates. The calculated adsorption/desorption isotherms and pore size distributions are discussed and compare well with nitrogen and water experiments. The standard method for pore size distribution determination from desorption data is evaluated. Second, the integration of the Korteweg liquid stress field around each cement hydrate particle provided the capillary forces at the nanoscale. The cement mesoscale structure was relaxed under the action of the capillary forces. Local irreversible deformations of the cement nanograins assembly were identified due to liquid–solid interactions. The spatial correlations of the nonaffine displacements extend to a few tens of nanometers. Third, the Love–Weber method provided the homogenized liquid stress at the micrometer scale. The homogenization length coincided with the spatial correlation length of nonaffine displacements. Our results on the solid response to capillary stress field suggest that the micrometer-scale texture is not affected by mild drying, while nanoscale irreversible deformations still occur. These results pave the way for understanding capillary phenomena-induced stresses in heterogeneous porous media ranging from construction materials to hydrogels and living systems.

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Section: Sorption Hysteresis and Pore Size Distributionscontrasting

confidence: 99%

Multiscale poromechanics of wet cement paste

Zhou

Ioannidou

Ulm

et al. 2019

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

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“…The difference of ice-water interface curvature is another possible mechanism for freeze-thaw hysteresis. In addition, sorption hysteresis (Pinson et al, 2018) and freezing-induced water redistribution (Mohammed et al, 2014) are also possible alternative mechanisms for hysteresis. Figure 3 shows the SFCC of nonsaline soil with various initial water contents (denoted by w 0 ).…”

Section: Water Resources Researchmentioning

confidence: 99%

Unified Soil Freezing Characteristic for Variably‐Saturated Saline Soils

Zhou

Meng

Wei

et al. 2020

Water Resources Research

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Freezing and thawing of soil have a significant impact on the thermal‐hydrological processes in cold regions. Freezing point and unfrozen water content are key variables characterizing the freezing and thawing of soil. The testing results show that unfrozen water content is independent of initial water content in nonsaline silt, based on which a unified model for a soil freezing characteristic curve (SFCC) is presented. The SFCC describes the relationship between unfrozen water content and temperature for variably‐saturated saline soils. It is also demonstrated that the SFCC can describe the variation of soil freezing point with respect to water content and salt concentration. The SFCC model is validated by comparing the experimental data to the calculated result for unfrozen water content and freezing point in a variety of conditions. When the initial water content varies in saline soil, the SFCC changes with constant initial salt concentration, but it remains unchanged with constant gravimetric salt content. The SFCC model can be adopted in the simulation of thermal‐hydrological processes in arid and saline lands and coastal regions. Finally, an example of thermal‐hydrological processes was simulated with the new SFCC model to show the application of the presented model.

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“…One argument is that this drop may be caused by measured water in capillary pores changing to in C-S-H pores [32]. Some studies believe that this is caused by cavitation of dissolved gas in pore solution [33,34]. However, the very steep sorption isotherm can also be caused by pore-blocking/percolation in a narrow range of pore necks [35].…”

Section: Fitted Sorption Isothermmentioning

confidence: 99%

Modeling Anomalous Moisture Transport in Cement-Based Materials with Kinetic Permeability

Zhang

Angst

2020

IJMS

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The durability of reinforced concrete structures is closely related to moisture state in cement-based materials. Therefore, it is crucial to develop moisture models that can accurately predict moisture state in the materials. However, many studies reported anomalous moisture transport in cement-based materials that cannot be well simulated by the conventional models. Several reasons have been investigated in the literature, such as the complex pore structure, chemical reactions with water, dimensional changes of the tested specimen, etc. Nevertheless, only a few models are able to capture the anomaly of moisture transport. This study viewed the main moisture transport coefficient—permeability—as a kinetic variable that depends on both the degree of moisture saturation and the contact time. The time-dependence was formulated by the decay (for drying) or growth (for wetting) functions. The saturation-dependence was calculated by the van Genuchten–Mualem (VGM) model. These functions were then implemented into a moisture transport model that was developed in previous studies. The proposed model was validated by experimental data and showed a good agreement for cement pastes that were dried or wetted in the hygroscopic range. Numerical simulation results were also compared with the simplified solutions to a fractional derivative model (FDM) of anomalous diffusion and the empirical Weibull function. We found that the solutions to the FDM cannot provide appropriate results. Weibull function performs as well as the proposed model, but the empirical function lacks physical meanings.

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Inferring pore connectivity from sorption hysteresis in multiscale porous media

Cited by 47 publications

References 87 publications

Multiscale poromechanics of wet cement paste

Multiscale poromechanics of wet cement paste

Unified Soil Freezing Characteristic for Variably‐Saturated Saline Soils

Modeling Anomalous Moisture Transport in Cement-Based Materials with Kinetic Permeability

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