Characteristics of Fly Ash as a Constituent Material for Geopolymer

Abstract Fly ash waste from the Asam-Asam Power Plant in South Kalimantan continues to increase. Various attempts have been made to utilize fly ash waste, among others. as a basic material for making geopolymers. Geopolymer is environmentally friendly because it replaces all cement with high Silica (Si) and Alumina (Al) wastes such as fly ash. This study aims to characterize fly ash as a raw material of geopolymer. Fly ash was filtered using 200 mesh and then heated in an oven at 105°C for 24 hours. The prepared fly ash was then tested for physical properties and compound analysis using XRF, identification of chemical bonds and functional groups using FTIR, morphology, and elements using SEM EDX. Initial and final setting time was investigated using the Vicat apparatus to determine e whether cement is undergoing proper hydration. The results indicated that the fly ash was classified to class F. That was based on the amount of SiO 2 + Al 2 O 3 + Fe 2 O 3 of 85.91%, and the CaO content was less than 10%. Moreover, fly ash’s initial and final setting time was 1072.5 and 3180 minutes, respectively. Fly ash in this research can be used as a raw material for geopolymers.