Title: Evaluation of Beneficiated and Reclaimed Fly Ashes in Concrete
Author(s): Saif Al-Shmaisani, Ryan D. Kalina, Raissa Douglas Ferron, and Maria C. G. Juenger
Publication: Materials Journal
Appears on pages(s): 79-87
Keywords: alkali-silica reaction; beneficiation; fly ash; pozzolanic reactivity; sulfate attack; workability
With the availability of ASTM C618 Class F fly ash decreasing, fly ash suppliers are working to find materials to meet demand by beneficiating ashes that do not comply with specifications and reclaiming ponded or landfilled ashes. The performance of three beneficiated and two reclaimed fly ashes was evaluated in this study by testing: 1) workability of paste, mortar, and concrete; 2) pozzolanic activity using isothermal calorimetry, portlandite consumption, and compressive strength of mortar and concrete; and 3) the ability to suppress expansion due to alkali-silica reaction and sulfate attack. Mixtures containing the fly ashes were compared against control mixtures containing portland cement and either a “production” fly ash or an inert quartz filler. All the beneficiated and reclaimed fly ashes are able to perform similarly to a production Class F fly ash, with differences in performance generally linked to particle size and shape following grinding.