LABORATORY PERFORMANCE ASSESSMENT OF CONSOLIDATED CRUSHED SALT FOR BACKFILL MATERIAL IN POTASH MINE OPENINGS

Abstract

The objective of this study is to experimentally determine the strength and deformability of crushed salt as affected by applied stresses and consolidation period.  The crushed salt has grain sizes ranging from 0.075 to 4.76 mm.  The optimum brine content is determined as 5% by weight.  The consolidation tests are performed by applying constant axial stresses to the crushed salt samples installed in the 54 mm diameter steel cylinders.  The axial stresses are 2.5, 5, 7.5 and 10 MPa.  The uniaxial compressive strengths are measured after the samples have been consolidated for 3, 5, 7, 10 and 15 days.  The axial strains are monitored and used to calculate the magnitude of the consolidation for each specimen.  The consolidation magnitude and density of the crushed salt samples increases with the applied stresses.  The uniaxial compressive strength increases with the consolidation.  The porosity decreases as the consolidation increases.  The test results are used to develop a set of empirical equations to design the initial installation parameters in terms of the physical and mechanical properties of the crushed salt as backfill material in potash mine openings.