This article discusses the microstructure, strength, and durability of geopolymer mortar constructed using low calcium fly ash (Class -F). Geopolymer mortars are made by combining fly ash and sand with an alkaline solution (Sodium hydroxide (NH) and sodium silicate (NS)). The ratio of fly ash to sand is 1 to 1, with a constant rate of alkaline liquid to fly ash of 0.55 and NS/NH ratios of 1.5,2,2.5,3, respectively. The geopolymer mortars for the ambient and oven-cured samples were made by varying the NH concentrations to 2, 4, 6, and 8M. The curing temperature of 60oC for twenty-four hours kept the geopolymerization active. The results indicated that the thick polymerisation gel development in the SEM pictures and XRD analysis explains the presence of the mineral Microcline and sodium-calcium silicate and is consistent with the findings of the EDS analysis. The SEM photos reveal the production of a robust polymerisation gel. The XRD data quantified the percentage of minerals created, making the material suitable for construction to fulfil present and future needs.