This study aims to investigate the stabilization of black cotton (BC) soil using mine waste (MW) and steel slag (SS) to enhance properties of the subgrade for pavement construction. The purpose is to explore the combined effects of MW and SS on the strength of subgrade and thereby promoting sustainable construction practices.
The methodology involves laboratory tests on BC soil and BC soil stabilized with various dosages of MW to determine the optimal BC soil–MW mix. Subsequently, SS is added to the optimal BC soil–MW mix to further enhance its engineering properties. This study uses a series of tests including California bearing ratio (CBR), durability tests, scanning electron microscopy (SEM) and X-ray diffraction (XRD) to assess the microstructural changes and strength improvements in the stabilized soil mixes. In addition, finite element modelling using ABAQUS software is performed to evaluate the performance of pavement structures designed with the stabilized soil mixes. This approach is cost-effective due to the availability of MW and SS in the study area.
CBR test results showed that optimal mix of 60% BC soil, 40% MW and 30% SS exhibited a CBR value of 7.8% and an effective CBR of 5%. The durability test results show that the stabilized mix with SS has a weight loss of 10.8% after 12 cycles of wetting and drying, within the permissible limit of 12%. SEM and XRD analyse reveal significant improvements in the microstructure of the soil, transitioning from amorphous to crystalline due to the formation of cementitious compounds. This study also demonstrates that incorporating a cement-treated base (CTB) layer in the pavement structure-II (PMS-II) leads to better performance and durability compared to a conventional pavement structure-I (PMS-I). Furthermore, life cycle cost analysis and life cycle assessment indicate that PMS-II offers a 16% reduction in initial construction cost, a 49.4% reduction in maintenance cost and a 71.9% reduction in total carbon footprint compared to PMS-I, highlighting its potential as a sustainable pavement solution.
The study area is surrounded by BC soil and mining activities. Steel industries generate waste in the form of SS, and hence, the utilization of these materials in road construction leads to solid waste management and economic benefits.
The study emphasizes synergetically adding MW and SS by replacing them with natural materials thus reducing the environmental impact caused by the materials due to their storage.
Study provides comprehensive evaluation of combined utilization of MW and SS for soil stabilization thereby offering economic and environmental benefits. In addition, the advantages of CTB layer in bituminous concrete pavements were explored. Overall, this study encourages the possible utilization of industrial waste for subgrade stabilization in pavements and underscores the benefits of CTB layers in pavements.
