MECHANICAL PERFORMANCE OF CONSOLIDATED CRUSHED SALT MIXED WITH MgCl2 BRINE FOR CARNALITE MINE BACKFILL

Abstract

Mechanical properties of consolidated crushed salt mixed with 5% MgCl₂ brine by weight are determined under different stresses and periods.  The crushed salt specimens with particle sizes ranging from 0.075 to 4.76 mm are consolidated under stresses ranging from 2.5 to 10 MPa for 7 to 90 days.  The consolidations strains increase rapidly within the first 7 days and tend to approach a limit value after 30 days.  The density, uniaxial compressive strength and elastic modulus measured after consolidation increase with the applied stress and duration.  The Poisson’s ratio decreases slowly with time.  The mechanisms that strengthen and stiffen the crushed salt mass are consolidation by volumetric change due to particle rearrangement and cracking, and healing between crushed salt particles.  The mean strain energy required during consolidation for each specimen is calculated.  The relations can be used to predict the crushed salt performance installed in potash (carnallite) mine openings.