Modified proportional model for time-dependent sieving

Sieving is a routine measurement that may provide additional information about soil physical properties such as particle shape. The usefulness of sieving for this purpose is restricted by limited empirical descriptions of the time dependence of the sieving process and the unclear influence of diluent particles. The purpose of this research was to (i) evaluate existing models to describe sieving curves, (ii) describe and evaluate a modified proportional model, and (iii) determine the effects of material mass, material type, and diluent particles on the sieving curves and model parameters. Glass beads and sand-sized particles were sieved, with the material passing being collected on a balance whose output was captured electronically. Five initial masses were used. Additional studies examined the influence of oversized particles (i.e., larger than the sieve opening) on the sieving process. Existing models were inadequate, but a modified proportional model gave superior fit, and its parameters (c and n) can be interpreted. The parameter n is insensitive to loading but is dependent on particle type and shape. Increasing oversized particles changes the time dependence of the sieving curves such that n decreases, showing a decreased effectiveness of passage at later times.