Structural similarity between dry and wet sphere packings

The mechanical properties of granularmaterials change significantly in the presence of a wetting liquid which creates capillary bridges between the particles.This results e.g. in a reduced value of the volume fraction when a packing is prepared with added liquid. Here we use x-ray tomography to demonstrate that this change in mechanical properties is not accompanied by structural differences between dry andwet sphere packings when compared at the same volume fraction.Wecharacterize the structure of the packings by the average numbers of contacts of each sphere «Z» and the shape isotropy «β₀ ^2,0» of theVoronoi cells of the particles.Additionally,we showthat thenumber of liquid bridges per sphere «B» is approximately equal to «Z» + 2, independent of the volume fractionof the packing.Thesefindingswill behelpful inguiding the development of both particle-basedmodels and continuummechanical descriptions ofwet granular matter.