A Dry Sieve Technique for Evaluating Particle Size of Gypseous Soils

Gypsum-rich soils defy fundamental characterization by silicate-based techniques. A key example is particle size analysis. Calcium derived from gypsum dissolution prevents dispersion, hence it (gypsum) it is routinely removed prior to PSA. Gypsum removal is tedious, time consuming, and the resultant fraction represents only the non-gypsum material. Particle size measured via normal methods has little interpretive value. Particle size analysis in liquids other than water (low viscosity oils or alcohols) also suffers from lack of dispersion and heat (drying) limitations imposed by gypsum. Field particle size estimates based on “feel” and visual observation are useful, but not quantifiable. We propose a dry sieve technique to obtain a consistent measure for particle size comparison. The data obtained is not a true particle size, but the technique provides a rapid estimate based on uniform energy input that can help quantify field texture. We will present results from a number of gypseous soils.