Variability qualitative phase composition of the different grain classes of the calcareous fly ashes

The results of studies of the phases composition of the different grain classes of calcareous fly ash were presented in this article. It was necessary to use three analytical methods: thermal, X-ray and microscopic to identify properly additional mineral phases in different grain classes of fly ash. These mineral phases were not determined during analysis of the sample which was not devided into grain classes. The minerals: quartz, anhydrite, calcite, bassanite, hannebahite hematite, magnetite, gehlenite, anorthite and CaO were identified. The thickest grain class of the tested ash characterized by a higher content of unburned fragments of coal. The presence of coal grains has negative influence at any further applications of the ash.