Isotropic behaviour of tailings sands with non-plastic fines at high pressures

Abstract

This article presents an experimental study that examines the isotropic triaxial behaviour of tailings sands in a wide range of pressures from 10 kPa to 5 MPa, varying the fine content of the tested samples. The results suggest that the presence and quantity of fines have influence in the behaviour: there is an increase in the compressibility of tailings sands deposited in a loose state, generating significant changes in the void ratio when confined throughout the range of pressures studied. In addition, it is observed that the effect of the fines in the compressibility decreases with the decrease of the void ratio, even exhibiting stiffening of the sample for the densest conditions of confection. Results of imaging performed post-test on the material suggest that the tailings sand exhibits a slight breakage of its angular edges when consolidated at high pressures. For low void ratios, differences in fines content of up to 4% are observed for clean sand. This difference decreases when the fine content of the sand increases, suggesting that the presence of fines contributes to the stability of the granular structure, redistributing the interparticle stresses, decreasing the level of breakage.