Correlating Quantitative Sand Shape Parameters to Agronomic and Engineering Properties.

Sands used in constructing root zones of athletic fields and golf courses are tested prior to construction to evaluate their suitability. The majority of the laboratory tests are quantitative, but particle shape is assessed qualitatively. The objective of this research was to quantify differences in particle shape complexity using a Camsizer and to correlate particle shape with properties of interest, like total porosity, bulk density, and bearing capacity. The Camsizer, a digital imaging machine presently used in the pharmaceutical and paint industries, provides a testing procedure that is applicable to current procedures practiced by American Association of Laboratory Accreditation accredited laboratories conducting root zone performance testing. This apparatus utilizes two cameras under controlled light conditions to take 60 images per second of particles as they fall randomly. Images are then analyzed and measured to produce shape parameters such as sphericity, aspect ratio, and symmetry. Five sands of various shapes were separated into the medium size class (0.25 – 0.50mm) to control variability introduced by particle size distribution. Glass beads were used as a rounded control and Black Jack, a sand blasting material, served as a very angular control. Significant differences between all treatments were observed for each shape parameter, indicating that this technology provides a method to quantitatively assess particle shape complexity. The Camsizer was also able to detect shape differences within various size classes of the same sand. All treatments were tested for agronomic and engineering properties at two moisture contents: oven-dry and 5% gravimetric water content. Sphericity showed the strongest correlation with total porosity, bulk density, and bearing capacity. The agronomic properties had a stronger correlation when tested in the oven-dry state, while bearing capacity was more correlated with 5% moisture content.