The objective of this study was to investigate the effect of particle size distribution on the mechanics of remolded, unsaturated, granular materials. Vibratory compaction, moisture retention, and unconfined compression tests were conducted on five power function gradations of sand and silt. Analytical studies of the equivalent pore pressure and pore size distribution were conducted to explain the mechanical behavior of the materials in terms of the effective stress Law;The exponent term in the power function used to describe the particle size distributions is shown to be a characterizing parameter of the compaction and shear strength behavior. This parameter provides a way to relate changes in dry density, moisture potential, and shear strength with moisture content for different materials;High gradation exponents (more uniform gradations) are shown to produce lower bulking in vibratory compaction, lower air entry pressures in moisture retention, and lower apparent cohesion in shear strength. Very low gradation exponents (high fines content) produce the highest air entry pressures and apparent cohesion, but low dry density under standard vibratory compaction. This is explained in terms of the high equivalent pore pressures found in fine particulate materials with fine pore structures;The results of the experimental and analytical studies conducted on the five sand-silt mixtures are used to develop a model of the expected handling behavior of crushed, bulk solid materials in gravity flow systems. This model is further developed into a classification system for prediction of handling problems in coal-fired power plants
