TWO-LANE HIGHWAY PAVING
For this stretch of U.S. 441, a warm mix asphalt was used for paving in lieu of the standard hot mix seen on many projects of this sort.
“A lot of asphalt plants are electing to go with the warmer mix—it’s just more cost effective,” Bittman explained. “And it’s a little bit for the environment. So the temperatures come in at 275° rather than your 320°. And you’re allowed 25° in both directions. Otherwise the mix is no good and you can’t put it down. And we had no loads rejected on this project either.”
According to Bittman, the contractor milled 3 in. of asphalt along the project and put back 3 in. in two lifts. The project went ahead of schedule, and the team experienced zero deficiencies on both the structure and friction lifts. “Deficiencies are checked by a rolling straightedge and they measure every sixteenth of an inch that the asphalt is off, so anything over 3/16 is considered out, and you got to repair it,” Bittman said. “We had zero, and we were running about 1,000 tons a day, if not a little bit more every day we were paving.”
The contractor said the biggest challenge during paving was coordinating the various steps in the paving process. “We probably had 10 to 15 dump trucks in front of the milling machine, and then the paving crews started maybe two hours later just to coordinate,” Bittman said. “You want to keep a good, steady speed with the paver. And that project we pretty much stayed at 25 ft a minute.”
Among the equipment the team used included a Roadtec paver, outfitted with MOBA’s big ski pole—which is about 30 ft long and is placed on the side of the paver right along the centerline. The ski pole is equipped with nine sensors in total, which allow the contractor to measure the correct depth in order to get the smoothest ride.
FDOT explained that the contractor was “very proactive” in obtaining informational roadway cores in order to monitor the quality of the mix in the lab and adjust the rolling pattern as needed to ensure minimum densities were consistently being met. This, FDOT said, resulted in 100% of the material placed on the project either meeting or exceeding specifications. The average composite pay factor for the asphalt was 1.03 with a total of 27,501 tons placed. After completion, FDOT performed laser profiling of the entire corridor, which resulted in zero deficiencies in a total of 18.8 miles tested. Both lanes of the project had an average ride number of 4.4 with no areas any less than 4.0.