Normal compression of tire derived aggregate particles

Elastomeric materials such as tire derived aggregate (TDA) are increasingly used in geotechnical engineering applications as an alternative lightweight backfill. Despite having similar shear strength to granular backfills, TDA has higher compressibility and exhibits creep under sustained loading. While continuum-level constitutive relationships have been developed to describe the compression response of TDA, the deformation response of TDA in terms of particle-to-particle interaction deserves further study to understand the fundamental mechanisms of TDA compression and permit TDA to be simulated using the discrete element method (DEM). The normal contact behavior of TDA particle pairs under normal loading and unloading is studied through an experimental program developed to capture the interaction between different shred types (tread or sidewall) and orientations (face, back, or edge). The TDA particle pair normal stress-strain curves were nonlinear and exhibited a hysteretic loading-unloading response even for lower ranges of stresses expected in geotechnical engineering applications. The stress-strain curves were found to be well-represented by a hyperelastic model to capture the nonlinear shape, combined with the Maxwell viscoelastic model to capture the hysteresis observed during unloading. This combined model is the first step toward development of a new contact model for TDA that can be implemented into DEM.