This paper focuses on the development of a geopolymer (GP) mortar that can be cured under ambient conditions using a combination of flash-calcined dredged sediment (FCS), Metakaolin (MK), granulated blast furnace slag (GBFS), and potassium silicate (K2SiO2) as an alkaline reagent (AR). The goal of this research is to reduce carbon emissions from traditional clinker-based materials by using valorized materials in the formulation of the geopolymer binder. The study investigates the effect of the alkaline reagent-to-binder ratio (AR/Bmm) and precursor composition on the mechanical and durability properties of the GP mortar. The results indicate that the lowest AR/B ratio and formulations with higher GBFS percentages have better performance. Porosity test and microstructural analysis tests such as X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) was conducted to ensure the stability of the GP formulations exposed to a sulfuric acid attack test, while nuclear magnetic resonance (NMR) tests validate the Q4(1Si, 3Al) network and their assigned Si/Al ratio. The leaching examination concludes that the GP design is not classified as hazardous materials. © 2023 Elsevier Ltd