Digitally Quantifying Sand Particle Shape and Particle Size Distribution: Resultant Effects on Root Zone Bearing Capacity.

The overall objective of this research was to improve sand selection for constructing and maintaining putting greens and athletic fields by more accurately predicting the bearing capacity of sand textured root zone materials. The specific objectives were to: characterize particle size distribution and shape of sands currently used to construct root zones utilizing a novel dynamic digital image analysis technique; quantify performance criteria and bearing capacity of current root zone materials; and utilize a stepwise regression analysis to select the most influential variables that contribute to the California Bearing Ratio and develop a model to predict its value. Fifty three sands were characterized by mechanical sieve analyses and their performance criteria (bulk density, hydraulic conductivity, total porosity, aeration porosity, capillary porosity) were measured. A dynamic, digital imaging machine was used to quantify particle sphericity, symmetry, and aspect ratio. The California Bearing Ratio (CBR) was measured for each sample following vibratory compaction in the laboratory. A stepwise regression analysis indicated that a total six variables significantly contributed to predicting the CBR value (R²=0.7517). These variables were coefficient of uniformity (Camsizer), coefficient of uniformity (mechanical sieve), sphericity, sand content, coefficient of variation, and percent retained on the 0.15mm screen.