Open-cast mining produces large quantities of solid waste, mainly in the form of overburden (OB) soil, and its effective management is a key concern for the mining industry. Additionally, coal-fired electricity generation produces significant amounts of fly ash. The main objective of this study is to utilize mine OB soil along with fly ash-based geopolymer for pavement base layer applications. Two types of base layers from mine waste were investigated: the first is a base layer prepared with manufactured artificial aggregates made from a mixture of mine OB soil and fly ash-based geopolymer, and the second is base layer from mine waste treated directly with a fly ash-based geopolymer. The geopolymer-treated base used a mix of 50% mine OB and 50% fly ash with a liquid alkali activator, composed of sodium hydroxide and sodium silicate. pH-based Eades–Grim approach was employed to determine the optimal NaOH concentration. Unconfined compressive strength and repeated load triaxial tests were conducted on treated waste for curing time of 7, 14, and 28 days to assess the effects of curing time. The results indicated that the 7-day UCS met IRC 37-2012 requirements, with only a marginal increase in resilient modulus values beyond this time, making it optimal blend for faster construction. A comparison of resilient modulus characteristics between the artificial aggregate and geopolymer-treated mine waste, and natural aggregate showed that the geopolymer-treated specimens exhibited superior resilient modulus properties. Further investigations, such as durability and water absorption tests, are needed to assess the suitability of these base layers, with future research recommended.