Mine overburden material (OBM) is the discarded soil-rock mixture, which is abundantly dumped around coal mines. These dumps create a lot of instability and environmental issues. The present study attempts to sustainably utilize the mine OBM in the construction of mine haul roads. Mine OBM is generally a soil-rock mixture with differently graded materials lacking the specific requirements for use in pavement subgrade. To utilize the OBM, stabilizers like lime and cement alone may not work due to the heterogeneity of the OBM. Hence, Road Building International (RBI) grade 81, a novel calcium-based stabilizer was used in this study to increase the mechanical properties of the soils, as it can stabilize various ranges of soils. The collected soils were silty sand (SM), intermediate compressible clay (CI), and clayey sand (SC), which possessed different plasticity characteristics. To assess the strength properties of modified mixtures, the California bearing ratio (CBR) and unconfined compressive strength (UCS) tests were conducted along with rutting resistance at different curing periods. The study shows that increasing RBI content enhances the soaked CBR values, with a peak of 135% for stabilized mixtures (SM) soil stabilized with 4% RBI. While the UCS values rose 16 to 18 times, reaching 1,355 kPa for intermediate compressive clay (CI) soil with 4% RBI. Wheel tracking tests demonstrated a 5 to 30-fold reduction in rut depth, dropping below 1.5 mm at 520 kPa stress, even at lower RBI levels for all composite mixtures. The use of RBI has proven to be effective in increasing the subgrade performance for all types of soils in OBM, while for CI soils it is more effective.

Mine haul roads are the unpaved roads that are constructed from the overburden materials obtained from the mining operations and are used for the movement of heavily loaded dumpers and trucks. The haul roads constructed from this overburden material shows continuous distress in the form of over ruts, potholes, and shear failures, creating major issues in the movement of dumpers. In the present research study, an experimental investigation was conducted based on mechanistic empirical design to evaluate the strength-deformation characteristics, durability, and environmental emissions of cement stabilized overburden soil of a local mine. The unconfined compression tests were conducted at cement dosages varying from 1 to 6% of dry soil mass and increase in the unconfined compressive strength were examined at different intervals of time until 28 days of the curing period. In the case of static triaxial tests, the enhancement in undrained shear strength and elastic modulus of stabilized specimens was determined in comparison to the untreated specimens, whereas in cyclic triaxial tests, the reduction in permanent deformations and increase in resilient modulus were evaluated under different confining pressures and cyclic deviatoric stresses. An empirical model has been proposed to predict the long-term rutting of overburden under repeated loading. The proposed model is based on the behaviour of various parameters, such as applied cyclic deviatoric stress, number of load repetitions, loading frequencies, and on the permanent deformation characteristic of mine overburden soil. In addition, durability and environmental sustainability aspects of the treatment has also been studied to determine the optimal dose of cement.