Title: Fluidized Bed Combustion (FBC) Fly Ash and Its Performance in Concrete
Author(s): Mona Zahedi and Farshad Rajabipour
Publication: Materials Journal
Appears on pages(s): 163-172
Keywords: anthracite coal; ASTM C618; benefication; bituminous coal; fluidized bed combustion; fly ash
Concerns over the availability and quality of conventional fly ash for use in concrete has become widespread in recent years. Fluidized bed combustion (FBC) ash, with its annual U.S. production exceeding 14 million tons, could serve as a reasonable alternative. In this study, two compositionally different fly ashes from circulating FBC (CFBC) power plants were evaluated for their compliance with the ASTM C618 standard and their impact on the fresh and hardened properties of concrete. The pozzolanic reactivity of the fly ashes was also quantified based on the emerging RILEM test method. These fly ashes met the chemical and physical requirements of ASTM, except for elevated LOI (in both fly ashes) and elevated SO3 (in one fly ash). Despite this, concrete with proper slump, air content, and strength development could be produced by proper dosing of chemical admixtures. The elevated SO3 was found not to produce deleterious expansions.