title: How relative humidity affects random packing experiments.
abstract: The influence of relative humidity (RH) on the extremely slow compaction dynamics of a granular assembly has been experimentally investigated. Millimeter-sized glass beads are considered. Compaction curves are fitted by stretched exponentials with characteristic time τ and exponent δ, which are seen to be deeply affected by the moisture content. A kinetic model, taking into account both triboelectric and capillary effects, is in excellent agreement with our results. It confirms the existence of an optimal condition at a relative humidity ≈45% for minimizing cohesive interactions between glass beads. The exponent δ is seen to depend strongly on the diffusive character of grains and voids inside the packing: diffusion for cohesiveless particles and subdiffusion when cohesion plays a role. As a consequence, the RH represents a relevant parameter that should be reported for every experimental work on a slowly driven dense random packing.
authors.affiliation: GRASP, Université de Liège, B-4000 Liège, Belgium.
authors.forename: N
authors.initials: N
authors.lastname: Vandewalle
authors.forename: G
authors.initials: G
authors.lastname: Lumay
authors.forename: F
authors.initials: F
authors.lastname: Ludewig
authors.forename: J E
authors.initials: JE
authors.lastname: Fiscina
mesh_terms: D003102:Colloids / Q000737:chemistry*; D003198:Computer Simulation; D006813:Humidity; D008956:Models, Chemical; D008958:Models, Molecular; D014867:Water / Q000737:chemistry*
chemical_list: D003102:Colloids; D014867:Water