Abstract: In view of the serious pollution caused by the large-scale storage of red mud to the surrounding environment, soil formation of red mud is a feasible method to realize the large-scale consumption of red mud and reduce its environmental harm. In this study, red mud was dealkalized using dilute sulfuric acid, and then mixed with different proportion of geopolymer solid waste and sugarcane waste residue. The physical and chemical properties of the mixed matrix were analyzed to explore the synergistic effect of geopolymer solid waste and sugarcane waste residue on the soil formation process of red mud. The results show that after acid washing, the pH value of red mud decreases from 11.30 to 7.11, and the content of Na decreases from 10.711% to 0.750%, with the dealkaization rate is as high as 93%. After mixing with 30% (mass fraction) geopolymer solid waste, the pH value of red mud increases from 7.12 to 8.21, and the porosity and non-capillary porosity increases from 43.43% and 3.31% to 61.35% and 13.40%, respectively, both meeting the requirements of “Planting soil for greening” (CT/J 340—2016). After further mixing sugarcane waste residue with a mass ratio of 40%, the organic matter content of artificial soil increases significantly from 6.7 g/kg to 28.5 g/kg, the non-capillary porosity further increases to 20.39%, the available water content from 6.88% to 16.16%, the proportion of large aggregates increase, and ryegrass grow well.

Key words: red mud, geopolymer solid waste, sugarcane waste residue, porosity, available water content, aggregate