VAA Virginia Asphalt Spring/Summer 2021

32 SPRING/SUMMER 2021 process mixture was placed contiguously with a two-layer SMA overlay, which will serve as the control for in-service perfor- mance comparison. The second field trial △ continued from page 31 VTRC PROGRAM OVERVIEW SPRING 2021 20 18 16 14 12 10 8 6 4 2 0 16.0 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 0 100,000 Raw Average Rutting (mm) Rut Depth at 8,000 Cycles, mm Sample A Sample B Sample C Sample D ESALs 45% RAP Optimized AC = 6.8% 30% RAP Optimized AC = 6.0% 200,000 300,000 400,000 500,000 600,000 Lane 2-5 B Lane 2-5 E Lane 2-3 E 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 Rut Depth at 8,000 Cycles, mm Sample A Sample B Sample C Sample D Production APA Results Figure 4: Actual Rutting Under the Heavy Vehicle Simulator (HVS) Compared to Rut-Susceptibility Results with the Asphalt Pavement Analyzer (APA) used a “dry” process ground-tire rubber system in a dense-graded mixture. There are three sections in this trial totaling approximately four miles each in the east and west-bound directions. The two-inch rubber-modified mixture was placed over a THMACO interlayer, placed over jointed concrete patched with an asphalt base mixture. Production and placement went well in both instances. Laboratory testing of the two modified mixtures suggests very good prospects for performance in one of the more challenging settings for an asphalt surface mixture. Hari and Shabbir will be completing some Texas Overlay Testing in the lab this summer and following up on the in-service condition for each trial (and control when available). Expect final reports for these projects by late fall 2021. Closing As spring arrives in Virginia, we look forward to another busy construction (and field research) season. They may still be behind a mask, but VTRC researchers will continue to be out among the folks who build, maintain, operate, and rebuild Virginia’s most visible public asset. Please ask them questions, and be generous with your ideas and opinions. And please, please be patient with them. They may be world-class nerds, but they mean well!