Research on Compressive Tests of Iron Tailing and Cement-Modified Earth Materials from Northwest China

The strength of earth-modified materials is an important mechanical indicator of raw soil building materials. Iron tailings are a rich mineral waste resource with basic properties similar to river sand and can be used as a modified material for raw soil construction. To increase the utilization rate of iron tailings and improve the mechanical properties of earth materials, modification of earth materials were analyzed using iron tailings and cement. Through a single lattice theory design method, 10 different blending ratios of modified earth specimens were designed, with each group comprising six 100 mm cubic specimens. Earth specimens were used as the control group and compression tests carried out under standard curing conditions, with analysis of the failure mode, compressive strength, deformation, and load–displacement curve for each specimen. Also, the reasons for specimen failures were examined, including the influence of strength, dispersion, and implications of load–displacement curves. The optimal mix ratio of modified materials was determined using frequency domain analysis method. The results showed that the load–displacement curves of materials with different material ratios were basically similar and the slope and discreteness of the curves quite different. Increased tailings and cement content improved the compressive strength of earth materials and increased the discreteness of the material. Through frequency analysis, it was obtained that when the content of tailings was 12.1%–19.5%, cement content 13.9%–19.1%, and earth 65.5%–69.9%, there was a 95% of the guaranteed rate of compressive strength of iron tailings and cement-modified earth materials between 6 and 9 MPa. Iron tailings can, thus, be used as the preferred material for modifying earth materials; single lattice theory can be used as the design method for mixing experiments, and frequency domain analysis can be an effective calculation method for optimizing mixing design. Adding cement and iron tailings to modify the raw soil formula can provide reference for the selection of basic materials for raw soil construction.