In this paper, selected laboratory test results for GRMs are presented, and the influence of adding granulated rubber on the macro-scale engineering properties (i.e., compaction, compressibility, shear strength, energy absorption, small-strain shear stiffness and dynamic properties) of GRMs are described. Then, using the newly developed DEM4GRM model, the force anisotropy, load-transfer mechanism and strong-force network at the particle-to-particle scale are examined and the change in skeleton material from stiff gravel-like to soft rubber-like is described.