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Title: Reclaimed Coal Ash as a Supplementary Cementitious Material: Productive Reuse including Chemi-mechanical Beneficiation

Author(s): Daniel Benkeser

Publication: Web Session

Volume: ws_S21_Benkeser.pdf


Appears on pages(s):



Date: 4/1/2021

As the United States energy sector has shifted from coal combustion toward natural gas and other renewable energy sources, the availability of fly ash has varied, leading to increased interest in the identification of alternative sources of supplementary cementitious materials (SCMs). One promising option is the utilization of previously ponded or “reclaimed” coal combustion residuals, including reclaimed fly ash. This study examines thirteen reclaimed coal ash samples for compliance with the ASTM C618 standard. These results indicate that many reclaimed ashes retain pozzolanicity, as measured through strength activity index (SAI), with nine of the thirteen ashes passing SAI requirements. Despite this, six of the thirteen samples did not meet ASTM C618 requirements, including exceeding limits on loss on ignition and particle size. For those ashes that did not meet SAI requirements, a novel and low-cost beneficiation process through chemi-mechanical grinding was examined. Processed ashes showed increases in the amorphous content by 5-36%.