Effects of the Duration of Landfill Disposal on the Physicochemical, Mineralogical and Toxicity Characteristics of Coal Ash

ABSTRACTThe quantities of coal ash disposed of in landfills over the past decades add up to billions of tons. Weathering in landfill would impact the mineralogical, chemical, physical and toxicity characteristics of coal ash. In order to investigate these effects, ashes were obtained from different depths of landfills representing different durations of disposal. These ashes were subjected to a range of physical, chemical, and toxicity tests. Aging in landfill was noted to produce significant changes in various ash properties. The trends in these changes with increasing disposal duration were identified. These trends were explained based on the weathering and leaching effects experienced by the coal ash in landfills. In addition, hydraulic activity and reactivity of the landfill coal ashes were determined to assess their potential use in alternate cement production.