Kentucky Highway Investigative Task No. 24, "Recycled Concrete Pavement", (SSP-059-7965) involved the use of Recycled/Crushed Portland Cement Concrete (RPCC) for use as Crushed Stone Base (CSB) on the Thomas More Parkway in Kenton County, Kentucky. The Parkway, which connects Dudley Road to South Loop Road in front of the Thomas More College campus, was the first roadway to be built in Kentucky using recycled Portland Cement Concrete for crushed stone base. The Kentucky Transportation Center was requested to evaluate the material's performance versus the normal limestone CSB and make appropriate recommendations. Both field and laboratory testing were required, along with annual visual surveys. In addition to the Thomas More Parkway, a portion of lnterstate 275 was studied, where both RPCC and virgin limestone were used for DGA in adjacent sections. The adjacent sections were used for testing and evaluation of the RPCC CSB to compare its performance with regular limestone under similar conditions. In addition, RPCC samples were also collected from Interstate 75 and analyzed.

At this time, it appears that the RPCC CSB is performing equally to the limestone DGA under field conditions. Considerable breakdown of the recycled aggregate was observed under laboratory freeze-thaw conditions, but laboratory gradation tests show that the aggregate on the project is still within the specifications for both DGA and CSB. Due to this laboratory breakdown of the aggregate, it is recommended that FWD and gradation tests, and visual surveys be performed on the Thomas More Parkway and I-275 periodically. However, since field performance currently appears to be the same for DGA and RPCC, it is recommended that RPCC could continue to be used as a substitute for DGA, unless future distress data indicate otherwise.

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