“We’ve had a lot of very positive experience with Wirtgen mills, Vgele pavers and Hamm rollers,” Byrum said. “We’ve had great success with the rollers, and I’m a huge fan of the millers. The Vogele pavers are well-designed and work well for us. When you look at what was specified, and the choice in machines, it was pretty much a slam-dunk for us.”
The specified split-drum rollers enabled the drum sections to turn at slightly different speeds on tight radii. “Because of the sharp corners that we had to pave and compact, the split-drum was ideal for making those tight turns,” Byrum said. “If you don’t use the split-drum, the mat will shove and push and cut on those sharp turns.”
Outside of the sharp turns on the binder course, the HD+ 90 VV-S split-drum compactors also served as breakdown rollers in back of the pavers for all three courses. “The split-drum worked fine on the rest of the track too,” he said.
The pneumatic rollers served as intermediate rollers. “They kneaded and fixed the surface of the mat,” Byrum said. “This mix was somewhat tender so we kneaded it using those rollers. But on the wearing course, the pneumatic rollers were not allowed, except at the very end of the rolling train, and that was a whole other challenge.”
The AB 600-2 TP2 screeds on the Super 2100-2 pavers have a leading-edge tamper bar, and two trailing-edge pressure bars. The pressure bars were used in conjunction with the tamper bar in placing the limestone flex base and base course, but not the binder and wearing courses.
“For the binder and wearing courses we used the tamper bar in front, but not the pressure bars in back,” Byrum said.
“When we didn’t use the pressure bars we got about 88 to 89 percent density,” he continues. “When we turned them on we got 91 to 92. But our consultant preferred that we not use the pressure bars as the aggregate might fracture. In response we rolled it a little bit more.”
Specification for the binder course breakdown rolling was 94 to 97 percent density, and the rollers were getting 96. In general, density specs for each lift were in that range, with the wearing course a little higher.
“Everyone involved with this project – Austin, Wirtgen America, our distributor Cooper Equipment – all have given 110 percent, partnering together, to make this project a success,” Byrum said. “Those guys – our equipment consultants – were here whenever we needed them to help us be successful, and we could not have done it without them.”
Thumbs up from FIA
“Everything that I’ve seen so far has been absolutely first class, and the progress that’s been made since the last time that I was here is amazing,” said Charlie Whiting, who directs racing, safety and technical matters for FIA.
“The guys have done an awesome job, it really is quite fantastic. It’s built to the highest quality, exactly as we expected, and I’ve got absolutely no complaints whatsoever.”
Whiting visited in mid-September, about two months before Formula 1 racing was to take place at the track. All Formula 1 circuits must be inspected and approved by Whiting before they can conduct Grand Prix racing, and the motorsports veteran spent approximately two hours touring the facility along with representatives of COTA, general contractor Austin, and German track architects Tilke GmbH.
Whiting approved the circuit for Grade 1 status, which is the highest distinction awarded to a motorsports venue. The passing grade cleared the way for the circuit to conduct Formula 1 racing this fall.