Utilization of discarded bauxite tailings into eco-friendly foamed mixture lightweight soil

Abstract

Large quantities of discarded bauxite tailings (BTs) are produced and pumped into the tailing reservoirs for a long time, which not only occupies large space but also causes damage to environment. This paper transformed discarded BTs into eco-friendly foamed mixture lightweight soil (FMLS), which was mainly composed of cement and foam without high temperature calcination. The fresh properties, durability, uniaxial compression performance and microstructure of FMLS with BTs (FMLSB) were investigated. 10%, 20%, 30% and 40% replacement percentages (by weight) of BTs for cement were considered. In terms of FMLSB and FMLS with fly ash (FMLSF), the percentage of the fly ash kept the same with the cement. Reference FMLS without BTs and fly ash was fabricated so as to investigate the influence on the material. The results revealed that the wet density of FMLSB was lower than that of FMLSF under equivalent replacement percentage. The unconfined compressive strength of FMLSB and FMLSF decreased exponentially with the increase of the replacement percentage of BTs and fly ash. Moreover, the unconfined compressive strength of FMLSF was higher than that of FMLSB under equivalent replacement percentage at the same curing age. The volume water absorption of FMLSB was higher than that of FMLSF, and the water stability coefficient of FMLSB and FMLSF were both higher than 0.7. The pore size of FMLSB and FMLSF was mainly between 1 mm and 2 mm. The skeleton area porosity of FMLSB was less than 20.33% when the replacement percentage of BTs was less than 30%. The application of BTs not only consumes a large amount of waste and reduces environmental pollution, but also alleviates the shortage of land resources and creates considerable profits.