Effect of Particle Surface Roughness on Densification of Coarse‐Textured Soil

Abstract

AbstractIt has been observed that soils on the Atlantic Coastal Plain compact to different bulk densities under the same compactive effort. It is hypothesized that densification differences observed among Ap horizon materials of these soils are partially due to variations in soil particle surface roughness. Surface roughness of Coastal Plain soil materials and sand size fractions derived from these materials were photographed and/or characterized by measuring the dense soil angle of response (DSAR) over a range of bulk densities. Altering the particle size distribution of a given material did not significantly influence the DSAR vs. Db (soil bulk density) relationship; the slopes and intercepts of these linear plots were not statistically different. However, plots of DSAR vs. Db for materials with different particle surface roughness had similar slopes, but different intercepts. It is proposed that the intercept of the DSAR vs. Db curve, or the value of DSAR at a given Db, be used to characterize soil particle roughness for coarse‐textured materials.It was further hypothesized that the DSAR at a given Db was directly related to particle packing arrangement stability, or resistance to further densification, of the soil material. To test this hypothesis, different levels of vibrational energy were applied to materials with different particle roughness but similar particle size distributions. Soil materials with the smoothest particles, i.e., those with the lowest DSAR at each Db, consistently produced the highest Db at each vibrational energy level.