The primary objective of this study was to investigate the feasibility of implementation of the crumb rubber technology in Kentucky. The impetus for this study was provided by the lntermodal Surface Transportation Efficiency Act of 1991 (ISTEA).
This study included an overview of existing literature on the subject from an implementation point of view for Kentucky's conditions. Upon completion of this phase of the study, guidelines were developed by the KTC research team and were submitted to the Transportation Cabinet for field implementation of the crumb rubber modifier (CAM) technology in Kentucky. From the ease of implementation point of view, the Cabinet opted to build a field trial section using the "wet process" which utilized a fine ground rubber (80 mesh) material. The rationale for this decision was based upon the fact that the fine ground CAM mix closely resembles the polymer modified HMA, and that both the Cabinet and Kentucky contractors have an extensive amount of experience with polymer modified asphalt.
In July 1993, a field trial project was constructed on a portion of the US 421, Franklin County, Kentucky. The project involved milling of nominally one inch of the wearing surface followed up by a nominally one-inch overlay. The four-lane trial project (two lanes in each direction) was divided into two approximately half-mile sections. This allowed for a comparison of performance between the CAM hot mix asphalt (HMA) and the conventional HMA.
In summary, the trial implementation of the CAM technology in Kentucky proved to be a success. The 80-mesh fine ground rubber at 7.5% by weight of asphalt cement provided a material similar to polymer modified asphalt. Construction of the field project was possible with existing specifications and practices in Kentucky. The non-intrusive nature of the fine ground technology was most desirable from the ease of implementation point of view.
Digital Object Identifier
Mahboub, Kamyar C. and Hancher, Donn E., "Development of Guidelines and Performance for Asphalt Concrete Containing Recycled Rubber" (1993). Kentucky Transportation Center Research Report. 570.