Geopolymerization emerges as a pioneering, environmentally sustainable, and eco-friendly technology within the construction sector. It utilizes industrial by-products to create alkaline-based mortar from source materials like copper slag, fly ash, metakaolin, and ground granulated blast furnace slag (GGBS). In this experiment, the compressive strength of copper slag geopolymer-added poorly graded sand was evaluated at room temperature over specific curing periods of 7, 14, and 28 days, with varying concentrations of NaOH. Additionally, the tensile strength was assessed after 28 days of curing at ambient temperature, using different molar concentrations of NaOH. To address challenges related to the appropriate mixing ratio and technique, the quantity of alkaline solution for proper mixing of all the elements was determined by adjusting the mixed alkali solution with a specific weight of the precursor (copper slag). The molarity of the sodium hydroxide (NaOH) solution was a critical factor in this process. Results indicated that copper slag-based geopolymer with different alkaline concentrations displays distinguished improvement of the strength and bonding of the river sand efficiently. The results of the copper slag-stabilized sand also rivaled 8% (OPC) cement-treated sand, showing some promising improvement in copper slag-stabilized sand compared to cement-stabilized sand. It is concluded from this study that copper slag-based geopolymer presented potential applications in mortar and ground improvement applications.