Geopolymer is an attractive construction binder owing to its ability to improve the properties of the concrete and preserves the environment from the high CO<jats:sub>2</jats:sub> emission. Geopolymer technology will convert the potential hazardous industrial waste such as fly ash into valuable construction materials. However, there is a need of studying the properties of iron-based geopolymer in order to enhance the fundamental and knowledge of the geopolymer research also development in this study area. Fly ash which contains a significant amount of iron oxide (Fe<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>) was used as a precursor and tested at different curing duration (1, 3, 7, 14 and 28 days). Crystallization of iron oxide (Fe<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>) contained in the fly ash under geopolymerization process will be able to turn waste fly ash into a strong concrete materials, simultaneously creating a waste-to-wealth economy. Furthermore, the formation of fayalite detected from the microstructure characterization is mainly contribute to the strength development of the fly ash after 28 days curing.
