Characterisation and applications of magnesite mine tailings as subgrade and structural fill

Abstract

Magnesite Mine Tailings (MMT) is a kind of waste produced during the mining of magnesite ore. Due to open cast mining process, huge amount of tailings are generated and dumped as open landfill that leads to numerous environmental hazards in the vicinity. MMT from Salem mine dump site, India is collected and a series of laboratory tests related to physical, chemical, mineralogical, mechanical, electrical and thermal properties have been conducted to characterise the MMT as construction material. Further, the results are compared with the river sand and the conventional coarse aggregates. The results have indicated that the MMT can be used as aggregates in concrete for non-wearing surfaces, manufacturing of bricks, low thermal insulation panels, embankment and thermal insulation fills. Ordinary Portland Cement (OPC) and sand fractions of MMT are added to Black Cotton Soil (BCS) at different combinations and their geotechnical behaviours are evaluated through systematic laboratory analyses inclusive of standard Proctor compaction, Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR) and durability tests. The environmental compatibility of stabilised mixes is examined using Toxicity Characteristic Leaching Procedure (TCLP) test. The stabilisation mechanisms are investigated using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Energy-Dispersive X-ray spectroscopy (EDX) analyses newline