This study addresses the critical need for sustainable and environment-friendly practices in road construction by investigating the feasibility of using recycled concrete aggregate (RCA) as a complete substitute for natural crushed stone in the base layer of pavements. Significantly, it proposes a solution that not only reduces the environmental burden of construction waste but also conserves natural resources. Its primary objective is to evaluate the technological and environmental viability of incorporating RCA, enhanced with clay soil, into the base layer design of pavements. Given RCA’s non-cohesive and non-plastic nature, this study added clay soil to the base layer in proportions of 5% and 10% (determined to be optimal through repeated trials). It employed a robust methodology, including laboratory testing of RCA, clay soil, and crushed stone to observe mechanical and physical engineering properties. Tests such as gradation, modified proctor, California Bearing Ratio (CBR), Los Angeles abrasion resistance, specific weight, absorption ratio, soundness, Atterberg limits, and permeability were conducted to ensure comprehensive analysis. The findings highlighted that the CBR values of the RCA-clay soil mixtures significantly exceeded those of crushed stone, emphasising the superior bearing capacity of the proposed material. In conclusion, the study demonstrated that RCA, when mixed with clay soil, offers a sustainable alternative for road base layers, providing enhanced structural performance while addressing environmental concerns. This study contributes to advancing green construction practices and offers a practical framework for integrating recycled materials in infrastructure development.