Laboratory Evaluation of Cement Stabilized Base Mixes Using Copper Slag as Fine Aggregates

Abstract: The utilization of innovative waste materials in road construction is steadily gaining importance in India and globally due to growing concerns about waste disposal, environmental sustainability, and the depletion of natural resources. This study presents a laboratory investigation into the use of granulated copper slag as a partial replacement for natural aggregate in the base layer of bituminous pavements. The objective was to assess the engineering properties of various mixtures of copper slag and natural aggregates stabilized with cement. Initially, the physical and chemical characteristics of copper slag were evaluated to determine its suitability for road construction. Then, three different mixtures, 0% CS + 100% NA, 10% CS + 90% NA, and 20% CS + 80% NA, were stabilized using 3%, 5%, and 7% cement by weight. The effects of copper slag content, cement binder content, curing period, unconfined compressive strength, wetting-drying cycles, indirect tensile strength, and modulus of resilience were analyzed. Based on the UCS strength criteria outlined in IRC 37 (2018), an optimum binder content of 7% cement was identified. The durability of the specimens was also assessed, with weight loss limited to around 2% after wetting-drying cycles. The ITS was found to be in the range of 8% to 16% of UCS for samples with 7% cement. Mixtures containing 7% cement met the strength requirements specified by IRC, making them suitable for use in the base layer of bituminous pavements. A five-layer bituminous pavement analysis was performed, in which vertical compressive strains on the subgrade and horizontal tensile strains at the bottom of the cement-treated base (CTB) layers were evaluated. The results support the recommendation of using the 7% cement-stabilized copper slag mixtures for the base layer in bituminous pavement structures.