Mechanical and microstructural properties of silt roadbed filling improved with cement, red mud and desulfurization gypsum

To investigate the potential use of Red mud (RM) and desulfurization gypsum (DG) in dealing with roadbed filling, a series of laboratory tests, such as compaction tests, unconfined compressive strength (USC) tests, water stability tests, basic physical-chemical properties tests and microscopic tests were conducted on the abandoned silt (AS) from Foshan, Guangdong. The results indicates that the strength and water stability of cement-treated AS increase with the addition of RM and DG. The UCS of specimens with the addition of 3% RM and 2% DG increases by 23.33% than that of pure OPC after 60 days of curing. Meanwhile, the water stability coefficient of DG-RM-OPC treated AS is increased by 0.41% to 14.42% compared to OPC treated AS, especially for C5RM6DG4, whose water stability coefficient is increased by 14.42%. The main reason can be attributed to the collaborative effects between RM and DG, under which the SiO2- 4 provided by DG reacts with the Al3+ provided by RM to promote the formation of AFt. The research results show promising application of RM and DG in cement-treated AS, and provide a reference for the utilization of AS, RM and DG.