Title: Evaluation of Alternative Fly Ashes as Supplementary Cementitious Materials
Author(s): X. Wirth, D. Benkeser, N. N. Nortey Yeboah, C. R. Shearer, K. E. Kurtis, and S. E. Burns
Publication: Materials Journal
Appears on pages(s): 69-77
Keywords: amorphous glass; ASTM C618; biomass; co-fired; loss on ignition (LOI); performance-based design
Due to changes in energy production and increased emissions regulations, fly ashes that meet specifications for concrete production are becoming increasingly limited in North America. Woody biomass ash, ash from coal that has been co-fired with small amounts of biomass, and previously geologically disposed, weathered coal fly ashes are each vast and geographically distributed potential sources which could augment the limited supply of “on-spec” or ordinary fly ash. This study characterizes a range of these alternative ash sources to assess if they fulfill the physical and chemical requirements and the strength performance index in ASTM C618. Changes to ASTM C618 that address the current fly ash production environment are recommended, including broadening the definition of fly ash to allow for reclaimed weathered ashes, co-fired ashes, and blended ashes that meet prescriptive and performance specifications.