Ryan Hurley

Granular media and concrete are the ubiquitous natural and construction materials. X-ray tomography (XRT) has been used throughout the past three decades to qualitatively and quantitatively study the kinematics of deformation in these materials from meso- to microscales. However, quantifying the microscopic mechanisms of stress transmission and energy dissipation in these materials has traditionally been limited to 2D model materials or 3D numerical simulations. Such information can provide insight into the validity of microscopic contact laws, the statistics of forces and energy dissipation, and the pre- and post-failure load sharing within the materials’ microstructures.

In this talk, I will discuss experiments employing in-situ XRT and 3D X-ray diffraction (3DXRD) measurements during the deformation of 3D granular materials and cement. Using 3DXRD, each particle in the granular materials and cements acts as a stress gauge, providing both the local elastic stress tensors and the orientations of material points within the microstructure. I will highlight experiments with granular materials in which we quantitatively measured inter-particle forces, constitutive law parameters, per-particle fracture stresses, and energy dissipation mechanisms at each inter-particle contact. I will highlight an experiment on micro-concrete in which we quantified the stress distribution throughout the microstructure before and after fracture. I will discuss ongoing and future research directions in geomaterials with combined XRT and 3DXRD.