Utilisation of iron ore mine tailings for the production of geopolymer bricks

This study presents a methodology for making bricks, in a cost-effective and environmentally friendly manner, using the tailings produced from iron ore mines in Western Australia (WA). The study was based on the geopolymerisation process, which is known to conserve energy by reducing the emission of greenhouse gases. The reduction is accomplished by avoiding the processes of high temperature kiln firing, traditionally utilised when making bricks from sandy soils with high clay content. In this study, the sodium silicate was added to the mine tailings in powder form, as an activator for the formulation of the geopolymer bricks. The effects of the initial setting time, curing temperature, curing time and activator content on the unconfined compressive strength (UCS), water absorption and other durability properties of the bricks were investigated. X-ray diffraction analysis was performed to investigate the phase composition of the geopolymer bricks. The bricks achieved an UCS as high as 50.53 MPa for the optimum values of the parameters. Technically, the geopolymer bricks that were produced met both the American Society of Testing and Materials and the Australian Standards (AS) requirements for bricks. A cost analysis of the geopolymer bricks is also presented, and this shows that the cost of geopolymer bricks is lower than that of the commercial, fired clay bricks.