Field Performance Evaluation of Class C Fly Ash in Full-Depth Reclamation: Case History Study

Abstract

Class C fly ash is a coal combustion product from lignite or subbituminous coal obtained as a result of the power generation process. In recent years, efforts were taken to incorporate self-cementing fly ash into fulldepth reclaimed (FDR) material to improve the structural capacity of asphalt pavement base layers. In this study, existing asphalt pavement in County Trunk Highway (CTH) "JK" in Waukesha County, Wisconsin, was pulverized in place and mixed with fly ash and water to function as a base course. To evaluate the contribution of fly ash to the structural performance of the pavement, nondestructive deflection tests were performed with a KUAB 2m falling weight deflectometer on the outer wheelpath 4 days and 1 year after construction. The modulus of fly ash- stabilized FDR base course increased by 49% 1 year after construction. The structural capacity of the fly ash-stabilized FDR base course in CTH JK also has increased significantly as it ages, because of the pozzolanic reaction. The results of this study indicate that the FDR mixes with selfcementing fly ash may provide an economical method of recycling flexible pavements and reduce the need for expensive new granular base courses for road reconstruction.

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