Communication Dans Un Congrès Année : 2024

Capillary stress and structural relaxation in moist granular materials, Network dynamics: synthesis, structure and mechanical properties

Résumé

Capillary effects, such as imbibition drying cycles, impact the mechanics ofgranular 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 nano-granular 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 nano-grains assembly were identified due to liquid– solid interactions. The spatial correlations of the non-affine 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 non- affine 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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Dates et versions

hal-04968439 , version 1 (26-02-2025)

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  • HAL Id : hal-04968439 , version 1

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Katerina Ioannidou. Capillary stress and structural relaxation in moist granular materials, Network dynamics: synthesis, structure and mechanical properties. Network dynamics: Synthesis, structure and mechanical properties, Feb 2024, Les Houches, France, France. ⟨hal-04968439⟩
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