Digital Imaging Techniques for Assessment of Homogeneity of Granular Materials

Abstract

This study focuses on the use of digital image techniques to evaluate and develop quantitative measures of fabric for fine-grained granular materials to assess degrees of homogeneity and isotropy. The description of a procedure performed to prepare homogeneous cylindrical sand specimens is presented. Two techniques were performed to investigate the homogeneity. The specimens were preserved with an ultralow viscosity embedding epoxy resin, and they were allowed to cure prior to dissection for subsequent detailed analysis of the internal fabric. Digital imaging techniques were used to process and analyze various sections of the specimens. The analysis consisted of studying two specific fabric characteristics of the soil: particle orientation and local void ratio. Frequency distribution charts were plotted to assess the degrees of homogeneity and isotropy. Other invasive techniques were also used in some cases to assess the repeatability of the specimen preparation technique. Results indicate that the specimens were prepared with a high degree of homogeneity. Some degree of spatial variation was observed in the local void ratio evaluation.