The effect of fabric on the behaviour of gold tailings

Abstract

Undisturbed sampling of gold tailings, especially under the water table, is difficult and in many cases impossible. For this reason laboratory testing of tailings is generally conducted on reconstituted material. It has been shown that laboratory sample preparation methods can affect the mechanical behaviour of cohesionless soil and it is generally believed that the difference in mechanical behaviour is attributable to a difference in the fabric (particle arrangement) inherent in the preparation method. An experimental programme was conducted to (a) examine the fabric which ensues upon sample preparation and (b) to investigate the effect of any fabric differences on the mechanical behaviour of gold tailings. Comparison was made between the behaviour and fabric of undisturbed and reconstituted moist tamped and slurry deposited samples. The results from the experimental programme show that there is indeed a difference in fabric between undisturbed and reconstituted gold tailings samples. Slurry preparation generally replicates the fabric and behaviour of the undisturbed sample better than moist tamping, but neither fully replicates the undisturbed sample. At large strains, the samples reach a unique critical state friction angle, but at different stress states.