State of the Art - Use of Fly Ash and Concrete in the United States and Suggestions for Future Research

摘要

To try to accommodate the many new subbituminous fly ashes, the American Society for Testing and Materials (ASTM) established two classes of fly ash, Class F from bituminous coal and Class C from subbituminous and lignite coal. However, the wide variability of the Class C ashes from location to location led to extensive x-ray diffraction studies, with the conclusion that the mineralogy was more important than the chemical analysis and that the classification by type of coal was erroneous. There is a need to produce a performance-oriented standard rather than a prescription.rnRecently, the installation of No_x burners has increased the carbon content, the fly ash, and, consequently, the instability of entrained air in concrete.rnThis paper summarizes the state of the art on the use of fly ash and concrete in the United States and makes suggestions for future research.