In this study, mechanical properties, powder properties, thermal properties and phase properties of samples produced by sintering at different temperatures after alkali activation by geopolymerization, made from fly ash obtained from Sivas Kangal Thermal Power Plant, are discussed. Compression test for mechanical properties, transient plane source measurement for thermal properties, scanning electron microscopy for surface and powder properties, and X-ray diffraction for phase analysis were used. In studies, Na2 SiO 3, an alkali that can be found easily commercially and a source of silica, was used at different molarities and its properties were investigated. It was concluded that fly ash can be used both as a geopolymer and as a sintered material as a lateral plate as well as brick production. Compressive strength was found to be as 10 MPa, thermal conductivity is 0.0006 W/m.K, and the determined phases are calcium silicate, calcium aluminate, amorphous silica and magnesium aluminate and glassy kyanite which is a sintering product, namely aluminasilicate phase.