One-part alkali-activated materials (AAMs) with fly ash and ground granulated blast furnace slag (GGBS) offer mechanical performance similar to conventional concrete and improved environmental sustainability. This paper examines the fresh and mechanical properties of 27 AAM mixes with varying mix proportions. Key design parameters include activator/binder ratio (A/B) from 0.05-0.15, binder content from 460-1050 kg/m³, and fly ash/GGBS ratio from 50/50-10/90. Flow table and setting time evaluated the workability, and compressive and flexural tests assessed the mechanical properties. Carbon emission and cost assessments were also performed. One-part AAMs achieved compressive strengths of 66 MPa at 7 days and 76 MPa at 28 days. Mixes with low binder content (460 kg/m³) showed 4-28% lower compressive strength at 84 days compared to 28 days. Higher binder content (650-1050 kg/m³) and A/B (0.1-0.15) had increased compressive strength by 6-21% at 84 days than at 28 days. The mix with 0.15 A/B, 650 kg/m³ binder, and 30/70 fly ash/GGBS ratio performed best in a multi-criteria assessment that considers mechanical properties, embodied carbon, and cost.