Characterizing Surface Roughness and Shape of Sands Using Digital Microscopy

This paper presents detailed microscopic analyses of the surface roughness, roundness, and sphericity of sands. The surface roughness of three silica sands was studied using the optical interferometry approach. It was statistically characterized by a set of parameters. Optical interferometry yielded very accurate measurements of surface roughness of the three sands. It was found that, as the surface roughness increases, the friction and dilatancy angles of the sand increase. In addition, two new indices for particle roundness and sphericity are introduced, compared with the Powers classification, and used to classify the investigated sands.