Potential use of stockpiled circulating fluidized bed combustion ashes in manufacturing compressed earth bricks

There is currently 123 million tons of coal combustion by-products produced in US each year. Among these include fly ash, bottom ash, boiler slag, and flue gas desulphurization material. Of that approximately 40% are utilized as a construction material in cement manufacturing, roadway construction, and others. However, the utilization of some ashes such as those produced by fluidized bed combustion has been limited due to their inherent high sulfate and carbon content. This paper is aimed at the evaluation of the potential use of stockpiled circulating fluidized bed combustion ash (SCFBCA) to develop compressed earth brick (CEB). Laboratory tests were conducted to determine the physical, chemical, and mineralogical properties with respect to SCFBCA. A series of tests were carried out to evaluate the properties of the bricks related to filler and binder types on compressive strength, density, and absorption. Test results indicate that SCFBCA can be used to manufacture CEB. Subordinately, test results may provide a means to reduce a waste disposal problem while providing the brick industry with a new, useful, low cost raw material.