WEST VIRGINIA DOT
We plan a complete rewrite of our design RAP requirements. Currently, we require the use of a blending chart per the old AASHTO standard. We look forward to discussing potential changes with other DOTs at the Indy Pavement Recycling Summit in October.
UTAH DOT
We are implementing HiMod High Density HMA pavements on our interstate and high volume pavements and bridge decks. This came out of our demonstration project back in 2021 at the I-80 Wendover POE where we placed a 6 inch lift with PG 76-34 binder and achieved full depth compaction at 97 percent. We are using is a 50 gyration 1 to 1.5 percent void mix with a minimum 6.0 percent binder (6.2 percent for bridge decks), VFA required is 90 to 95 percent. This typically comes out at nearly zero voids with 75 gyrations. We have completed multiple project this year with full bonus on density, with the higher requirement target of 96 percent. This mix is also very rut resistant, typically at 4 mm rut with 20,000 passes in the Hamburg with a water temperature of 54 C. IDEAL-CT numbers are around 800 to 1000. The cost for this mix has come in under that of SMA. Our 13 mile project this summer on SR 196 had an installed price of $103 per ton. Bridge decks and smaller projects have been higher. We are consistently achieving 96 percent compaction on bridge decks (3 to 4 inch lifts) with only static rolling.
IOWA DOT
Updated PWL payment schedules based on a 10 year review and analysis.
MICHIGAN DOT
We created an optional PWL spec for SMA mixtures that pay based on Air Voids, Vbe and Density, our normal pay factors are AV, VMA, AC content and Density. The goal was to create a spec that was fair to the contractor and DOT and encourage good quality mix that was being penalized under the old spec but was performing well in service. We recently changed our PWL spec to raise the upper AC content limit to 0.50 from 0.35. We had been seeing projects where 1 or 2 sublots were in the +0.35 to +0.50 range that were performing well in the field and not exhibiting any concerns with too much AC in the mix.
OHIO DOT
At the beginning of 2023, Ohio DOT started requiring a minimum dosage of antistrip for mixes that contain coarse gravel, more than 25% natural sand, or more than 20% RAP that contained coarse gravel. At the beginning of 2023, we also started pilot projects with PWL for density and will gradually increase over a three-year implementation period. We used average of 10 cores previously.
NCAT invites comments and questions submitted to Steven Stiefel at sds0082@auburn.edu.