A REVIEW ON THE USE OF SECONDARY MATERIALS AS AN ALTERNATIVE FOR STABILIZING EXPANSIVE SOILS

Abstract

This paper examines the impact of various admixtures aimed at enhancing strength and minimizing deformation characteristics of black cotton soil, based on research conducted by multiple scholars. The stabilization of black cotton soil is focused on ensuring the creation of stable and long-lasting engineering structures. This process becomes essential when the materials designated for foundation and pavement construction do not fulfill the standards required in civil engineering practices. Black cotton soil from the north-eastern region of Nigeria, as well as from various global locations, is predominantly categorized as A-7-6 soils by the American Association of State Highway and Transportation Officials (AASHTO); classified as CH high plasticity clay soils by the Unified Soil Classification System (UCSC); and identified as high swell potential black cotton soil by the Nigerian Building and Road Research Institute (NBRRI). The experiments conducted include Atterberg’s Limits, Specific Gravity, Sieve/hydrometer Analysis, Free Swell, Compaction, Triaxial, Shear Box, Unconfined Compressive Strength (UCS), and California Bearing Ratio (CBR) tests. Soil properties such as maximum dry density (MDD), optimum moisture content (OMC), CBR values, shear strength, cohesion, and angle of internal friction were significantly enhanced by admixtures including lime, cement, E-waste, reclaimed asphalt pavement, and steel mill ore. In contrast, admixtures like groundnut ash, bagasse ash, and plantain peel powder showed inadequate improvement when utilized independently. Therefore, it can be concluded that black cotton soil, when stabilized with admixtures such as lime, cement, reclaimed asphalt pavement, E-waste, and steel mill ore, is suitable for use in foundation and pavement construction. This study ultimately recommends the combined use of weaker admixtures with certain cementitious materials to achieve a robust and durable foundation.