Evaluation of Mechanical Properties and Environmental Impact of Red Mud-Based Silty Soil Modified by Inorganic Binding Materials

Red mud (RM) is a byproduct of aluminum production, and silty soil (S) has poor engineering characteristics. The enhancement and utilization of RM and S in highway engineering are suggested to address these problems. Therefore, the mechanical properties of red mud-based silty soil (RMS) under different modified materials and their impact on the environment should be investigated. Unconfined compressive strength test, splitting tensile strength test, microscopic test, and environmental index tests were conducted on the modified red mud-based silty soil with varying cement (C), lime, and fly ash (LF) contents. The results show that when the red mud content is 20%, cement-modified red mud-based silty soil (C-RMS) exhibits the highest strength, as well as superior toughness and deformation resistance. At a red mud content of 23% and lime-fly ash content of 20%, lime-fly ash modified red mud-based silty soil (LF-RMS) demonstrates the highest strength and improved deformation characteristics. According to the Technical Guidance on the Construction of road surface infrastructure, C-RMS may be used for the base of secondary and intermediate roads (3.5 MPa~4.5 MPa) or the base of main roads (2.5 MPa~3.5 MPa). The LF-RMS may be used on the surface of motorways and main roads (≥1.1 MPa) or on the lower slopes (≥0.8 MPa). The environmental indices of LF-RMS are slightly inferior to those of C-RMS. This research provides valuable insights for future studies on the road use of red mud.