In this paper, self-sensing cemented soil composites were prepared using multi-walled carbon nanotubes and nano-magnetite as conductive fillers. The effects of mono-doped and co-doped multi-walled carbon nanotubes and nano-magnetite on the early mechanical properties, electrical properties, and self-sensing properties of the cemented soil composites under different forms of loading were investigated. The influence mechanism of multi-walled carbon nanotubes and nano-magnetite on the cemented soil composites was explored by scanning electron microscopy. The results indicate that the incorporation of nano-magnetite has the potential to enhance the early mechanical properties of cemented soil composites. While multi-walled carbon nanotubes enhance the integrity of the conductive network within the cementitious soil, they also mitigate the influence of the polarization effect. The dispersion of multi-walled carbon nanotubes in cemented soil composites can be enhanced through the co-doped multi-walled carbon nanotubes and nano-magnetite, thereby increasing its electrical conductivity. Furthermore, the co-doped multi-walled carbon nanotubes-nano-magnetite not only enhances the stress sensitivity of the cemented soil composites but also sustains a favorable linear relationship between cracks and electrical resistance changes, thereby facilitating more precise and comprehensive crack monitoring.

The extraction and processing of iron ore produce significant amounts of mine tailings, causing environmental problems that require storage in reservoirs or dams. Using these materials in construction helps minimize their adverse impacts. This study analyzed the geotechnical properties of Magnetite and Hematite iron ore tailings (MIOT, HIOT) from the Golgohar mine in Sirjan, Iran. Two IOTs were compacted using the Standard Proctor technique after being treated with 5, 7, and 9 % Portland cement. Following curing time, treated samples were tested at different stress levels for resilient modulus. Based on the results, to meet strength and durability requirements, cement-treated MIOT needs 9 % cement. Contrastingly, only 5 % of the cement for cement-treated HIOT met the criterion. The resilient moduli of untreated MIOT and HIOT materials heavily rely on the confining pressure, resulting in a minimal decrease in modulus by increasing deviatoric stress. The effect of cement on resilient modulus is more pronounced in high confining stresses than in low confining stresses in MIOT and HIOT materials. A comparison of different non-linear models showed that 'Universal' model is the best fit for laboratory results of cement-treated MIOT and HIOT materials, as it accounts for hardening and softening behavior.

Purpose: The research examines the variation of soil erodibility index and physical characteristics due to iron placer mining activities and assesses the environmental impact of mining project by using MICOLD matrices.Methods: The research employed field samplings, laboratory analysis, and statistical analysis to study the variation of soil erodibility index and physical characteristics caused by iron placer mining activities. The study collected soil samples from the study area and conducted laboratory analysis to examine the physical and chemical properties of the soil. Statistical analysis was performed to analyze the data and identify the variation in soil erodibility index compared to natural conditions. Also, by modifying ICOLD matrices, environmental impact assessment of the project was evaluated.Results: The results of the paper indicate that there are significant differences between treated and untreated soils in terms of physical and chemical properties. The soil erodibility property (Ks) differs by -14.71% from natural conditions in top soils, although not significant statistically. In subsoil, Ks, clay, sand, Sp, Cu, Zn, Mn, Fe, and K differ significantly from untreated conditions (-43.38%, 35%, -15.07%, 5.28%, -192.50%, -242.55%, -101.86%, -333.34%, and -31.41%). The matrix of prediction and identification of the impacts related to the implementation of the mining project was created in two phases (construction phase and exploitation phase), the results of which show the total points in the construction phase and the exploitation phase have positive impacts and are equal to +71 and +171, respectively.Conclusions: The study examines the effects of iron placer mining operations on soil erosion characteristics and erodibility and suggests environmentally friendly solutions for minimizing the effects of mining on soil erosion. The research findings highlight the importance of considering physical characteristics of soils such as texture, infiltration, bulk density, and soil erodibility in evaluating the performance and efficiency of any project implemented on the Earth's surface. It emphasizes the need for designing well-operated devices and structures with little environmental damage to promote eco-innovation and green growth. The paper suggests that the environment is the most critical aspect of green surface mining, followed by efficiency and safety, and highlights the importance of microorganisms in mining environments and their role in constructing and producing primary succession for plant communities.