This study examines use of geopolymer concrete (GPC) as a sustainable alternative to Portland cement-based concrete by investigating the influence of varying proportions of ground granulated blast furnace slag (GGBS) and fly ash (FA) on the compressive strength of GPC 8M alkaline solutions. Mix designs were formulated with GGBS-to-FA ratios of 80:20, 60:40, 50:50, 40:60, and 20:80. Additionally, alkaline-to-binder ratios of 0.30, 0.34, 0.38, 0.42, 0.46, and 0.50 were also considered to study their effect on compressive strength, along with aggregate proportions of 1080 kg/m3 (67%) and 1174 kg/m (70%). Compressive strength test was conducted on 100 mm x 100 mm cube specimens after 7 and 28 days of ambient curing. Results showed that increasing alkaline-to-binder ratio enhanced workability, leading to improved compressive strength. Mixes with higher GGBS content exhibited greater compressive strength due to high calcium content in GGBS, which accelerated geo-polymerization. However, higher GGBS proportions reduced workability due to the material's rapid reaction rate. The findings of the study revealed that the compressive strength of GPC is significantly influenced by GGBS-to-FA proportion and the alkaline to-binder ratio. An alkaline-to-binder ratio of 0.38 was found to provide optimal performance, balancing workability and compressive strength. Further, the results of the study underscore the potential of GPC as a high-strength, eco-friendly construction material due to the effective utilization of industrial by-products such as fly ash and GGBS. In this paper, a Parameter called Binder Index is proposed to quantify the effect of GGBS, fly ash and molarity on the Compressive strength of Geo-polymer concrete developed at ambient room temperature.