Pozzolanic activity of stockpile ash: Comparison of test methods

The paper deals with the determination of the pozzolanic activity of coal-fired power plant fly and bottom ash deposited in stockpiles in the Czech Republic. The pozzolanic activity of the ash was determined using the Frattini test, modified Chapelle test, electrical conductivity test, and strength activity index. The ash collected from a stockpile was not found to display any pozzolanic activity by the methods utilised. However, milling the fly and bottom ash was shown to be the means of activating its pozzolanic properties. The study demonstrated the pozzolanic activity of the deposited ash notably increasing together with a growing time of milling and the associated increase in the specific surface area. Also, the research study presented here carried out the comparison of the individual methods regarding their effect on the pozzolanic activity and has revealed their good mutual correlation.