Variation in fly ash properties with milling and acid leaching

Coal-burning power plants that consume pulverized solid fuels produce large amounts of fly ash as a residue. Fly ashes have been used in construction, agriculture, metal recovery and water pollution control. This paper considers the variation in properties of fly ashes to be used in the field of construction. y 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.