MEASUREMENT OF UNIFORMITY AND ANISOTROPY IN GRANULAR MATERIALS

This study presents new experimental procedures, which make use of the advances in digital processing to study the uniformity and anisotropy of granular materials. Measurements of the microstructure parameters were made on resin-impregnated granular specimens. A new apparatus to conduct resin impregnation of granular materials has been developed to facilitate specimen preparations for microstructure observations. The nonuniformity of porosity distribution within a specimen was evaluated using imaging techniques. The anisotropy analysis consisted of the directional distribution of local porosity and orientations of solids and voids. The procedures have been used to study the fabric of granular specimens prepared from Ottawa sand, silica sand, and spherical glass beads. The relation between directional porosity and the preferred orientations of granular particles and voids was highly dependent on their angularity and elongation.