Properties and microscopic mechanism of MKP-modified magnesium oxychloride cement solidified red mud

The effects of magnesium oxychloride cement (MOC) and MKP (Mono potassium phosphate)-modified MOC on the properties of solidified and stabilized Bayer red mud (RM) were studied through the unconfined compressive strength test, durability tests, and microscopic characterizations. Results show that the solidifying effect of MOC can help RM achieve the necessary strength required as a road base or subgrade material in civil engineering. MOC can significantly improve the resistance to water immersion and wetting-drying cycles of RM. MKP has been demonstrated to enhance the resistance to water immersion and wetting-drying cycles of MOC-solidified RM. The mechanical behavior of solidified RM is closely related to the quantity and form of phase 5, the expansion and cementation of brucite, and the pore distribution of matrix. The primary mechanisms underlying the enhancement are attributed to the adsorptive affinity of RM for MKP and the modification of short rod-like phase 5 induced by MKP. • Solidifying effect of MOC helps RM achieve strength required as road base material. •MOC greatly improves resistance to water immersion and wetting-drying cycles of RM. •MKP help enhance resistance to water immersion and wetting-drying cycles of solidified RM. •MOC of 10 % concentration and MKP all can reduce the total porosity of solidified RM.