Center for By-Products Utilization IN-SITU RECYCLING OF DETERIORATED ASPHALT CONCRETE FOR NEW PAVEMENT BASE COURSES

Class C fly ash is a coal combustion product normally produced 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 full-depth reclaimed (FDR) asphalt pavements to improve the structural capacity of asphalt pavement base layers. In this study, an 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 using a KUAB 2M falling weight deflectometer (FWD) on the outer wheel path four days, one year, and two years after construction. The modulus of the fly ash stabilized FDR base course increased by 49% one year after construction, and by 83% two years after construction. The structural capacity of the fly ash stabilized FDR base course in CTH “JK” also increased significantly as it ages, due to the pozzolanic and cementitious reactions. The results of this study indicate that the FDR mixtures with self-cementing fly ash can provide an economical method of recycling flexible pavements and reduce the need for expensive new granular base courses for road reconstruction.