This study investigates the feasibility of producing sustainable Reactive Powder Concrete (RPC) through the incorporation of silica fume (SF) and waste mortar (WM) as partial replacements for cement and fine aggregate, respectively. Four RPC mixtures were experimentally evaluated using silica fume contents of 15% and 20% combined with 50% waste mortar replacement. The mechanical performance was assessed through compressive and flexural strength tests at curing ages of 7 and 28 days, supported by statistical analysis of the experimental data. The findings revealed that increasing silica fume content significantly enhanced the mechanical properties due to improved pozzolanic activity, matrix densification, and refinement of the interfacial transition zone (ITZ). The mixture containing 20% SF and 50% WM exhibited highest mechanical performance among the tested combinations, achieving compressive strengths of 103.18 MPa and 123.80 MPa at 7 and 28 days, respectively, in addition to a maximum flexural strength of 23.5 MPa. Also, the incorporation of waste mortar improved particle packing density and contributed to secondary hydration reactions, resulting in enhanced fiber matrix interaction and crack resistance. Statistical evaluation confirmed acceptable consistency and reliability for most RPC mixtures. The findings demonstrate that waste mortar can be successfully utilized in RPC production without compromising structural performance. While, a full life cycle assessment is required to quantify the exact ecological savings, this substitution highlights a promising avenue for enhancing the sustainability profile of (RPC) by reducing reliance on cement and natural sand.
