ABSTRACT

The characteristics and properties of different fly ashes depend on the nature of the fuel and the size of furnace used. Pulverization of solid fuels for the large furnaces used in power stations creates an immediate, urgent problem; dry fly ash has to be collected from the stack gases and disposed of quickly and safely. The similarity of some fly ashes to natural pozzolanas of volcanic origin has encouraged the use of fly ash in conjunction with portland cement in concrete making. Not all fly ashes are suitable for this application, however; unstable chemical reactions may have adverse effects on both the hydration process and the ultimate stability of the end product.