Volume Contraction and Reduction in Hydraulic Conductivity during Particle Crushing

Particle crushing takes place in a wide range of engineering applications and affects fluid flow through granular materials. This study examines volumetric changes and the evolution of hydraulic conductivity during particle crushing using a combination of high-stress experiments, data compilation from published studies and particle-scale numerical simulations. An asymptotically correct hyperbolic model fits void ratio versus stress data and provides reliable estimates of the yield stress. Alternatively, hydraulic conductivity follows a power law with void ratio and the trend extends into the grain crushing regime. Hydraulic conductivity diminishes rapidly as sand grains start crushing; the reduction in hydraulic conductivity can reach 1-to-4 orders of magnitude depending on mineral composition, particle shape and initial packing density. Crushing involves the progressive detachment of small fragments; these small particles move into the larger pores, increase the drag resistance, clog pore constrictions, and effectively hinder fluid flow after the yield stress.