Title: Twenty-Five Years’ Experience Using Fly Ash in Concrete

Author(s): Joseph F. Lamond

Publication: Symposium Paper

Volume: 79

Issue:

Appears on pages(s): 47-70

Keywords: bleeding (concrete); compressive strength; concrete durability; flexural strength; fly ash; freeze-thaw durability; fresh concrete; hardened concrete; gravity dams; mix proportioning; permeability; pozzolans;

DOI: 10.14359/6685

Date: 5/1/1983

Abstract:
The U.S. Army Corps of Engineers has used fly ash as amaterial that partially replaces portland cement in concrete for twenty-five years. Initially research was performed on use offly on concrete properties for bleeding, permeability, heat rise, resistance to freezing and thawing, elasticity, and compressive and flexural strength development. Those properties affected by partial replacement of portland cement with fly ash were heat rise in mass concrete, resistance to freezing and thawing and strength development. The concrete materials properties of three massive concrete gravity dams are reported. Since construction, these dams have been periodically inspected. Although these structures have some minor cracking, spalling, and erosion, their performance has been similar to other concrete gravity dams constructed using concrete without fly ash. Cost savings per cubic yard of concrete has been the benefit derived from using fly ash as a partial cement replacement material in massive concrete structures. Fly ash is specified to conform to ASTM C618, Class C or Class F with modifications to this specification as needed based on location or type of structure. Fly ash may replace portland cement up to 35 percent by absolute volume in interior mass concrete and 25 percent by absolute volume in exterior mass concrete and in structural concrete. Fly ash concrete has performed satisfactorily on Corps of Engineers projects over the last twenty-five years.