In a previous paper, Brouwers and Van Eijk presented a theoretical study on the dissolution (reaction) of pulverised powder coal fly ash. This fly ash was modelled as hollow spheres, and a shrinking core model was derived for these hollow spheres that contain two regions (an outer hull and an inner region). The obtained analytical equations were applied to the dissolution experiments by Pietersen, yielding reaction rates at various temperatures and pH for two class F fly ashes. Based on the observed trends, in the present paper a reaction mechanism is proposed for the glass phase which accounts for the oxide composition of the fly ash (and that is applicable to slags as well). Finally, using the reaction product, the following thermodynamic properties of the studied fly ashes are derived: the free energy, enthalpy and entropy of reaction. The values obtained are in
line with those of known substances: silica and an aluminosilicate (2SiO2.Al2O3)
