Concrete can incorporate substantial amounts of waste and industrial by-products, supporting the circular economy by reducing landfill use and promoting resource reuse. Sustainable mixtures present a promising solution in applications such as Buckling-Restrained Braces (BRBs), where concrete strength is not the primary concern. The partial replacement of Portland cement with locally available supplementary cementitious materials, such as limestone filler and glass powder (GP) derived from recycled glass waste, offers significant environmental and economic benefits. This study investigates the use of eco-efficient self-compacting concrete (SCC) as an infill material for BRBs. At this stage, mortar-level research was conducted to develop ternary binder formulations incorporating waste glass powder (GP) and limestone filler as a substantial cement replacement and to determine the optimal ratio for achieving the desired engineering properties. A factorial design approach was employed to enable the mathematical modelling of critical engineering properties, such as mechanical strength (Rc, 28d) and fresh-state characteristics (D-flow and T-funnel), as functions of key mixture parameters. These parameters include the water-to-powder ratio (Vw/Vp), water-to-cement ratio (w/c), GP-to-cement ratio (GP/c), and superplasticizer-to-powder ratio (sp/p). The desirability function was then applied to the statistical model to identify the optimal combination of materials, water, and admixtures, achieving a balance between engineering properties and carbon efficiency. SCC ternary blends can be developed by incorporating both conventional and unconventional supplementary cementitious materials (SCMs). These materials allow for a high degree of cement replacement while maintaining the desired engineering properties for the intended application.