The construction industry significantly contributes to global carbon emissions, with concrete production playing a major role. This study investigates the potential of using fly ash as a partial replacement for cement (in varying percentages of 30%, 40%, and 50%) and recycled coarse aggregates (RCA) to reduce the carbon footprint of M20 grade concrete for manhole covers. Mechanical strength tests, including compressive, tensile, and flexural strength, were conducted at 7, 14, and 28 days. The results consistently indicated a decrease in strength with increasing replacement percentages across all three strength types. However, a 30% replacement level demonstrated a reasonable balance between strength retention and the use of sustainable materials. This study highlights the potential of utilizing fly ash and RCA in producing more sustainable concrete for infrastructure applications like manhole covers.