Variation in fly ash properties with milling and acid leaching

The fly ashes produced in two coal-burning power plants in Asturias (Spain) were physically and chemically characterized in order to determine their pozzolanic activity and reactivity. Fly ashes are used as hydraulically active additives as they are a finely divided inorganic material. They were examined to determine whether they could be used as special preservatives in cements and concretes. To improve their properties, they are mechanically activated by wet milling as well as chemically activated by leaching with 30% by weight sulfuric acid at different temperatures and times.