Strength and critical state characteristics of lime-stabilised mine tailings

This study examines the influence of molding conditions and curing time on the mechanical characteristics of lime-stabilized mine tailings. Consolidated drained and undrained triaxial tests were conducted on reconstituted specimens with varying molding conditions and curing times, with 6% lime content, under confining pressures ranging from 48 to 200 kPa. Multi-stage oedometric tests and constant head permeability tests were also performed under these varying conditions. Scanning electron microscopy, energy dispersive spectroscopy, and X-ray fluorescence were employed to analyze changes in particle morphology and chemical composition. The results suggest that the observed changes can be mainly attributed to two mechanisms: flocculation–agglomeration and pozzolanic reactions. The former occurs shortly after lime addition and appears responsible for increases in compressibility, permeability, and the slopes of the critical state lines (CSLs) in both the compression and p′– q planes. The latter mechanism progresses over time and is responsible for an increase in yield stress, the upward shift of the CSL in the compression plane, and enhanced shear strength due to cementation. However, this latter effect is only significant when the material is reconstituted to relatively high densities. The results provide valuable insights into the effects of lime stabilization on the mechanical characteristics of mine tailing materials.