Fly Ashes in Cements and Concretes: Technical Needs and Opportunities

摘要

Following a brief review of the nature of fly ashes and their levels of production and use in various countries, an estimate is made of the potentially achievable level of use of fly ash in cement and concrete in the United States. The estimate assumes that 20 percent of the mass of all the portland cement used in the United States could be replaced by the same mass of fly ash; it ignores possible competition from granulated blast-furnace slag as a finely-divided mineral admixture for concrete. It appears that about 16 million tons (18 million tons) per year of fly ash could be consumed in cement and concrete, provided there were sufficient ash of suitable quality and a general understanding of the technical requirements for satisfactory fly ash use. Present standards which affect the use of fly ashes are discussed. Steps which could be taken to improve knowledge of factors affecting fly ash performance in cement and concrete, and hence to improve standard test methods and specifications, are outlined.