Strength, deformation, and environmental impact assessment of cement stabilized mine overburden soil

Abstract

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.