Environmentally clean construction materials from hazardous bauxite waste red mud and spent foundry sand

• Published in: Construction & building materials 2019-12, Vol.229, p.116860, Article 116860
• Main Authors: Alekseev, Kirill, Mymrin, Vsevolod, Avanci, Monica A., Klitzke, Walderson, Magalhães, Washington L.E., Silva, Patrícia R., Catai, Rodrigo E., Silva, Dimas A., Ferraz, Fernando A.
• Format: Article
• Language: English
• Subjects: Bayer process’s red mud utilization; Environmentally clean construction materials; Mainly vitreous structure formation; Sintering till 1150 °C; Spent foundry sand
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2019.116860

•Were developed ceramics from industrial wastes.•Flexural strength of ceramics was till 10.54 MPa.•Values of water absorption coefficient was 2.77 and 14.41%.•New ceramics have mainly glassy structures with some crystal inclusions.•Utilization of industrial wastes will have high environment impact. This paper demonstrates the possibility of producing new red ceramics composites from red mud of hazardous bauxite waste (50–100 wt%), and foundry sand (10–50%) replacing the traditional clay-sand mix and preventing the environment pollution by such industrial wastes. The newly developed environment-friendly ceramics exhibit high physical properties (flexural strength, linear shrinkage, water absorption, and density). The ceramics’ analysis by X-rays fluorescence, X-rays diffractometry, atom absorption spectroscopy, scanning electron microscopy, energy-dispersion spectroscopy, and laser micro-mass analysis revealed the synthesis of mainly glass-like structures with a small inclusion of crystalline structures. The values of flexural strength reached 10.54 MPa; after sintering at 1150 °C, linear shrinkage varied between 6.62 and 7.92%, water absorption – 2.77 and 14.41% and bulk density – 1.65 and 2.07 g/cm3. The most valuable property of the developed materials is the ecological purity due to the heavy metal’s complete neutralization from both industrial wastes.