Characterization of an F-Class Fly Ash for Use as a Road Sub-base

Abstract

An F-class fly ash was tested in the laboratory for its physical and mechanical properties for use as a road sub-base in portions of a 2.1-mi (3.4-km) truck by-pass route in east-central Illinois. The testing showed that the fly ash would perform adequately and behave predictably as a road sub-base. Construction of the by-pass route started in early June 2002 and was finished in early September 2002. No unanticipated delays were encountered, and the performance of the fly ash fill exceeded expectations. Hopefully, these positive results will promote other projects around the country to use by-products of coal combustion products, especially fly ash, as suitable fill materials. This project was a co-operative development and demonstration effort among the Office of Coal Development and Marketing (OCDM) of the Illinois Department of Commerce and Economic Opportunity (IDCEO), Southern Illinois University at Carbondale (SIUC), Morgan County Highway Department (MCHD), Illinois Department of Transportation (IDOT), AmerenCIPS, and the Morgan County Regional Planning Commission. These agencies provided both funding and matching funds to carry this project to completion. The by-pass route was designed to move truck traffic around the southern and eastern sides of the small town of Meredosia, Illinois. One problem the proposed by-pass project encountered was the source of construction materials for the sub-base fill. The project needed an additional 77,000 yd.3 (59,000 m3) of fill for the sub-base. Because of the geology in the Meredosia area, one source of material for the sub-base was sand from a borrow pit. Several other possible sources were investigated, but most were too expensive for the limited budget. The alternative chosen was to use ponded F-class fly ash from the AmerenCIPS Meredosia power plant adjacent to the truck by-pass route. The first task of the project was to determine the physical and material properties …