Abstract
The effect of ratio of water to solids on undrained shear strength (tau(u)) by fall cone apparatus as well as the effect of volumetric cement content and porosity on the Unconfined compression strength (UCS) and modulus ratio (E-50/UCS) of Harmony and DRD tailings sands were investigated. 4% cemented fresh paste of 3:7 and 2:8 water to solid ratio were tested for tau(u) and samples blended with cement content of 2-7% and compacted to 80-95% of the maximum dry density were fabricated for UCS tests. The result revealed that for increase in water/solid of 13.60 to 49.20, tau(u) increased from 52 to 66 kPa and 32 kPa to 46 kPa for Harmony and DRD tailings respectively. For Harmony and DRD tailings stabilized with 2 to 7% cement content and compacted to 95% MDD, the UCS ranged from 0,81 MPa to 2.445 MPa and 0.954 MPa to 2.603 MPa respectively. The exponential relationships between the UCS, and the ratio of porosity to volumetric cement content (eta/Ccv) were strongly correlated with a high coefficient of determination (r(2)). The effect of threefold difference in non-plastic fines are most indicated by tau(u), E-50 and CaO - pozzolan ratio. Tailing sands that were blended with 35-% cement content and compacted to porosity < 0.35 met the local geotechnical specifications for mine backfills, flowable fills, and low traffic volume road layers.