Résumé
Capillary effects, such as imbibition drying cycles, impact the mechanics ofgranular systems overtime. A multiscale poromechanics framework was applied to cement paste, which is the mostcommon building material, experiencing broad humidity variations over the lifetime ofinfrastructure. First, the liquid density distribution at intermediate to high relative humidity isobtained using a lattice gas density functional method together with a realistic nano-granular modelof cement hydrates. The calculated adsorption/desorption isotherms and pore size distributions arediscussed and compare well with nitrogen and water experiments.The standard method for pore sizedistribution determination from desorption data is evaluated. Second, the integration of theKorteweg liquid stress field around each cement hydrate particle provided the capillary forces at thenanoscale. 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 ofnanometers. Third, the Love–Weber method provided the homogenized liquid stress at themicrometer 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 themicrometer-scale texture is not affected by mild drying, while nanoscale irreversible deformationsstill occur. These results pave the way for understanding capillary phenomena induced stresses inheterogeneous porous media ranging from construction materials to hydrogels and living systems.