Mechanical and Microstructural Assessment of Sand Stabilized with Alkali-Activated Copper Slag-Based Geopolymer: An Eco-Friendly and Sustainable Alternative Binder

Industrial processes generate vast quantities of byproducts, which pose significant environmental challenges. The production of conventional stabilizers like cement is energy-intensive and a major contributor to greenhouse gas emissions. In this context, geopolymerization has emerged as an innovative and environment-friendly sustainable alternative for the construction industry. Geopolymers, as the next generation of eco-friendly materials, have immense promising potential for replacing traditional cementitious products. This study focuses on the mechanical and microstructural properties of alkali-activated copper slag-based geopolymer, exploring its feasibility in geopolymerization. The experimental investigation of this study covers compressive strength, tensile strength, and mineralogical and microstructural analysis of treated sand. Compressive strength was tested at ambient temperature across various curing periods (7, 14, and 28 days) as well as after 7 days of oven-dried curing at 60°C. The minimum and maximum compressive strength recorded was 1.4 to 2.76 MPa at 5 and 15 M sodium hydroxide concentration, respectively, on 28 days of curing under ambient conditions; on the other hand, samples cured at 60°C show a remarkable maximum strength of 2.92 MPa within just 7 days. Tensile strength was assessed on the twenty-eighth day, with samples cured at room temperature and subjected to various concentrations of NaOH. The microstructural evaluation was performed using field emission scanning electron microscopy, while the mineralogical composition was analyzed by performing X-ray diffraction and energy dispersive X-ray techniques. The results demonstrated the strength and bonding of sand when stabilized with copper slag-based geopolymer, particularly at different alkaline concentrations. Further, the performance of copper slag-stabilized sand was compared with sand treated with 8% ordinary portland cement, revealing promising enhancements in the copper slag geopolymer system. This study shows that copper slag-based geopolymer shows promising ability as an alternative binding material, offering a possible reduction of carbon emissions to the environment.