Utilization of red mud for producing a high strength binder by composition optimization and nano strengthening

Abstract

Abstract Recycling of red mud (RM) has attracted more attention in recent years due to severe environmental problems caused by landfilling. The effect of composition optimization and Nano-strengthening on the properties of a binder based on RM was studied in this paper. Results showed that modifying ratios of main oxides and adding Nano-SiO 2 could obviously affect the mechanical properties and microstructure of the binder. Specimens with high SiO 2 /Al 2 O 3 molar ratio (S/A) displayed considerable increase in compressive strength, while decreasing Na 2 O/Al 2 O 3 molar ratio (N/A) improved the workability of the fresh mix. The compressive strength was developed significantly to be 45 MPa at 28 days by adding Nano-SiO 2 with 0.4 wt.% of RM. Phase transformation and microstructure change at different stages of RM decomposition and binder geopolyerization were investigated by X-ray diffraction (XRD), Fourier transformation infrared (FTIR) and Scanning electron microscopy (SEM). The results of this study may provide a prospective method to use RM more widely in construction applications.