Percolation of electrical and elastic properties of granular materials at the transition from a suspension to a loose packing

The behavior of elastic and electrical properties of granular materials at various consolidation stages was studied in two experiments: (1) Conductive spheres were immersed in a fluid with same density. We find that both elastic and electrical properties exhibit a critical behavior at the transition from a suspension to a loose packing. (2) We infer the distribution of bonds vs. pressure from conductivity measurements where conductive beads are mixed with smaller non-conductive beads. We find that the dependence of static elastic moduli on the number of bonds follows an effective medium theory type relation while dynamic moduli are rather insensitive to the number of bonds.