Fly ash and bottom ash from fluidized bed combustion power plants have limited use in the construction industry because of their high-inherited sulfate content. Therefore, most of these ashes are land-filled. Finite characterization, which included the determination of physical, chemical and mineralogical properties of such a land-filled ash from a circulating fluidized bed combustion power plant, was undertaken. The land-filled ash, which had been stockpiled for several years, was compared with freshly generated ash from this power plant. The tests performed included particle size distribution pattern, mineralogical, chemical, and water-soluble ions analyses, and morphological characterization using scanning electron microscope/energy dispersive X-ray analysis. The results indicate that a significant amount of the sulfate component in stockpiled ash was consumed in a reaction, which involved the formation of ettringite. The sulfate (anhydrite) in fly ash and bottom ash also converted to gypsum when landfilled, and lime in fly ash and bottom ash was spent due to weathering. The final objective of this research is to study if this stockpiled ash can be gainfully utilized in the production of a construction material. The characterization results suggest that the deleterious expansive reaction involving sulfate ions has been completed. Therefore, several potentials exist for utilization of the stockpiled ash; for example, in soil stabilization, road base construction and flowable fills.
展开▼
