Geopolymerization of Fly Ashes from 6 Indonesian Power Plants Using A Standardized Recipes

Abstract

Geopolymers were synthesized using fly ash as raw material from six steam power plants, Adipala (FA1), Indramayu (FA2), Paiton 9 (FA3), Asam-asam (FA4), Pulau Pisang (FA5), and Sanggau (FA6). Fly ash was tested for several characteristics using XRF, XRD, and SEM. XRF analysis showed FA1, FA4, and FA5 included in class C fly ash while FA2, FA3, and FA5 included in class F. The XRD analysis results showed that there were typical peaks of quartz, mullite, calcite, magnetite, and hematite in the fly ash samples. SEM analysis shows the morphology of the fly ash FA1, FA2, FA3, and FA4 spherical with different particle sizes, but in the fly ash FA5 and FA6, the morphological shape is irregular. The highest compressive strength test results obtained by geopolymers made from FA3 after 28 days with compressive strength values of 36.62 MPa. The intensity of the crystalline geopolymer phase decreases when compared to its fly ash. Geopolymer morphology shows the presence of unreacted fly ash particles.