Impact of matrix deformations on drying of granular materials

Abstract

Drying of deformable porous media is encountered in soil, paints, coatings, food, and building materials. During drying, capillary forces can displace solid particles and modify invasion thresholds, opening preferential paths for air to invade. Since drying rates are crucially dependent on liquid connectivity through the porous medium, they are affected by the drying patterns. We study the interplay between solid matrix deformation and drying patterns and rates, and the impact of pore-size heterogeneity and the confining stress in a granular material. We couple a pore-scale model of drying with a particle-scale mechanical model, to capture the two-way coupling between the evolving drying pattern and solid particle displacements. Our simulations show that for a low pore-size disorder, and low confining stress, matrix deformations are favorable and lead to preferential drying patterns which maintain high drying rates. This effect is observed throughout the drying process when the disorder is low, but disappears after breakthrough for low confining stress, indicating a different mechanism by which deformation can impact drying. These results could be significant for various industrial applications, including fabrication of advanced nano-materials, where patterned drying can be used to obtain the desired structure.