SYMPOSIA PAPER Published: 01 January 1990
STP25306S

Laboratory Testing of Lime Fixed Flyash and FGD Sludge

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The operation of coal-fired power plants results in generating a considerable amount of flyash and flue gas desulfurization sludge. The properties of such material have not been widely reported and little is known about the field performance of this material when placed in landfills. This paper presents the results of extensive laboratory testing programs on six different mixes with variable flyash to sludge ratio. Lime was added as a fixing agent. Also, field samples from two operating power plants were tested in similar fashion, and results are presented and compared to laboratory testing results. In addition, a test pad was constructed from material produced by one of the operating power plants, and samples taken from the pad were tested.

Fixation of the flyash and FGD sludge by combining them with lime produces a mixture with improved properties over the flyash and the sludge. Generally there is significant improvement in structural characteristics, especially strength, and reduction in permeability by more than an order of magnitude. Therefore, the fixed material, with good quality control, could be handled and compacted easily in landfill.

Observation indicates that strength increases with time and with increase in density. The increase in strength when the mix was prepared utilizing brackish water is an important aspect observed during the study. Permeability results measured on samples prepared in the laboratory were found to be much lower than those obtained from field samples. Also, permeability was found to decrease with increasing density.

Author Information

SOLIMAN, NN
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Developed by Committee: D18
Pages: 168–184
DOI: 10.1520/STP25306S
ISBN-EB: 978-0-8031-5130-7
ISBN-13: 978-0-8031-1285-8