Study on the Basic Engineering Properties of Slag-Silica Ash Solidifying Red Mud under Alkali Excitation

[Purposes] In order to meet the demand for co-utilization of industrial solid waste to solidify red mud, it is proposed to add industrial solid waste materials such as slag and silica ash to red mud, and use NaOH initiation reaction system to co-solidify red mud. [Methods] The strength, resistivity, hydration products, and microstructure of solidified red mud were tested by using unconfined compressive strength testing machine, digital AC bridge, X-ray diffractometer, scanning electron microscope, and synchronous thermal analyzer. The effects of curing agent ratio, alkali initiators dosage, and curing age on the basic properties of cured red mud were discussed. [Findings] The results show that the strength of solidified red mud can be improved by both single doping and compound doping of slag and silica ash, and the main function of alkali initiator is to stimulate the potential gelling activity of red mud. By optimizing the test ratio, the effect of compound doping slag and silica ash in red mud is the best. The unconfined compressive strength is used as the evaluation index. When the contents of slag, sodium hydroxide, and silica ash are 15%, 3%, and 3%, respectively, the 28 d unconfined compressive strength of solidified red mud reaches up to 13.12 MPa.