High RAP for high sustainability

Mercer Road serves as the feeder route to the Lexington/Bluegrass Airport and sees plenty of daily, heavy-load traffic from warehouses serving UPS, FedEx, Amazon, and other shippers. The Lexington/Fayette Urban County Government (LFUCG) was searching for pavement solutions that would provide improved sustainability, and the BATT Lab had a proven solution to offer. The lab had worked with a new combination of additives that not only extended pavement life, but also offered the opportunity to include a higher percentage of recycled asphalt pavement (RAP) to the asphalt mix.

Nancy Albright with LFUCG liked the idea, but she wanted to see lab test results and a demonstration project before completely buying off on the solution. The challenge we agreed to was to create a high-performance hot mix that would equal or beat the performance of their usual PG76/22 mix with 3/8” NASM and 20 percent RAP.

The two-inch mill-and-replace Mercer Road project was installed in September 2020 and shows no signs of cracking to date. The BATT Lab designed a PG 64/22 asphalt binder mix that combined a bio-oil to soften the RAP and a double dose of aramid fibers for reinforcement. The addition of the bio-oil and the aramid fibers allowed the RAP content to increase to 45 percent with no sacrifice in performance. The BATT Lab oversaw the installation which went down smoothly with no issues and was placed at the same time as the control mix to ensure accurate monitoring.

The winter of 2022 will begin to tell us how the pavement will perform over the long term. That’s when you see the cracks begin to appear, but based on our experience with other installations of this solution, we expect this product to come in perfect.