Chemical Activation of Low Calcium Fly Ash Part II: Effect of Mineralogical Composition on Alkali Activation

In the previous study preliminary investigations on the chemical and mechanical activation of low calcium fly ash were presented. The study revealed that sodium hydroxide in low concentration was the most effective chemical activator for the low calcium fly ash. The pozzolanic activity of a fly ash depends upon many parameters, most important of which are fineness, amorphous matter, chemical and mineralogical composition and the unburned carbon content. The present study uses various low calcium fly ashes for alkali activation to understand further the mechanism of low concentration sodium hydroxide activation. Compressive strength measurements, X ray diffraction, SEM and hydration calorimetry characterization techniques were used to understand what physical and chemical factors responsible for the effective sodium hydroxide activation.