By: April Goodwin, Contributing Author
Sunmount Corp. bought one of the first Ingersoll-Rand ABG pavers ever sold in the U.S. When company officials purchased the Titan 511 to lay untreated base, little did they know the German-made paver would assist them with several racetrack, runway and highway paving jobs in the years to come.
In 1995, the Roanoke, Texas-based company was contracted to put down aggregate base on the Texas Motor Speedway. “After we got the stone down, we asked what they were going to do about paving it,” said Danny James, mechanical supervisor. “They didn’t have a plan. So we took the Titan 511 and paved it . . . it was just lucky that we were there with the right paver at the right time.”
Since then, Sunmount has spent the past nine years perfecting their proc-ess—and it shows. James and his crew have paved several high-profile racetracks, including the Atlanta Motor Speedway, some more than once. In the process, they have acquired another Ingersoll-Rand ABG paver—the world’s largest—the Titan 525. “We recently finished our sixth track paving job,” he said, “and we get better every time.”
One of the reasons the company has been so successful at racetrack paving, according to James, is because the 14-member crew works as a team and has stuck together since that first speedway job in the Lone Star State.
Smooth to the finish
James said since Sunmount purchased the Titan 525 tracked paver it’s always working at either an airport or a racetrack. Three of the company’s racetrack paving projects took place at the Texas Motor Speedway in Fort Worth.
“We were there in 1996, 1998 and 2002,” James said. “Tracks don’t typically need to be repaved that often, but this one had some settlement problems. When that happens, it makes for a bad ride.”
Obviously, there are unique challenges associated with paving a speedway as opposed to a highway. For starters, the incline or banking in turns is approximately 24°.
“We have gravity working against us and we have to keep the paver steady on the slope,” said James. “Any jerks or movements are transferred directly to the mat and damage the quality.”
Sunmount depends on the paver to ensure overall mat smoothness and a 20-ft ABG VDT 120 high-density, fixed screed to place the asphalt. The screed is designed for high pre-compaction, decreased rolling work and optimum evenness of the paved mat.
“For racetrack paving, that’s the only way to go. When you’re transferring material up the bank in the auger channel, you need to turn the asphalt up on degree, too—and that won’t work on an extended screed because the material will get cold,” James said. “We reach 85 to 92% compaction with the high-density screed. We require around 96 to 98% total compaction. So most of our compaction is already complete before the roller even starts.”
Another challenge associated with paving on an incline is delivering the hot-mix asphalt (HMA) to the paver. James has devised a unique setup for applications such as the Texas Motor Speedway. A mobilized crane is placed on the inside of the track where the ground is flat. The crane hoists an auger and slat chain that serve as a conveyor. This makeshift conveyor travels alongside the paver, delivering HMA to the hopper.
“It’s much like a transfer machine, but it’s able to reach out 50 ft. We’ve built an insert hopper that fits the Titan paver, and we just sit it inside,” said James. “We’re careful not to touch the paver because we’re trying to maintain grade.”
The firm’s third paving project at the Texas Motor Speedway started with milling 4 in. of asphalt and laying the open drainage layer (ODL).
“There were problems drying water off the track after rain, and the ODL was put in place to minimize that problem,” James explained. “Water in the ground transferred through the ODL into a drainpipe. We laid the ODL first, 1.5 in. thick. Then we put down two layers of topping mix for a total of 3 in. of topping.”
James and his crews went to great lengths to ensure maximum smoothness along the joints.
“With the joints we made, you could put a mask on someone and drive them around and they couldn’t tell where they were on the track,” he said. “We actually had two men doing joint cosmetics full-time.”
The Texas Motor Speedway is approximately 60 ft wide, so crews were able to pave the width of the track in three passes with the 19-ft 8-in. screed. They employed an electric joint heater to tightly bond the joints.
This process began after the first pass around the track was completed. The crew used a grader that looked like a large pizza cutter to cut off the lower edge of the asphalt. This area was cut off because it was not sufficiently compacted since it had nothing to compress against.
“As we cut off the edge, we were left with a 90° angle that was compacted to more than 90% density. When we came back with our next pass, we used the electric heater right at the joint so it heated the tack to over 140°. At this temperature, the tack is really sticky, which makes it easy for the tamper bars to compact the joint against the next pass,” James explained. “This is especially helpful when you are making the passes a day or two apart. By reheating the tack, the joint is more tightly compacted. Once we’re finished, you can rub your hand over the joint and not even feel it.”
The Texas Motor Speedway project got under way in the heat of the summer, causing James to re-evaluate the working conditions. Texas is known for extremely high temperatures, and that year was no exception. The decision was made to work at night, when the temperatures were lower.
“It was the first time we paved at night. We started working at 2 a.m. and finished each day around 1 p.m.,” said James. “The polymer mix that we put down on the track had to come out to the paver at 340 to 350°. We couldn’t subject our team to that kind of heat when in 106° daytime temperatures.”
Illuminating the track at night was nothing new for the Texas Motor Speedway. When they host night races, they utilize a revolutionary lighting system that uses mirrors to simulate daylight without glare or shadows.
Since NASCAR drivers race at speeds up to 200 mph, paving a track is much trickier than laying asphalt on a highway, James said. “These tracks are required to be twice as tight as the best highway ride you’ll ever have.”
James said Sunmount’s success can be attributed in part to the company’s attention to detail.
“We take our time and do it right. We’ve paved the Atlanta Motor Speedway, which is the fastest mile-and-a-half in the world, and we’ve paved the Texas Motor Speedway, which is the second fastest. We do the best work out there as far as I’m concerned. It’s the result of how we attack each job and the high performance of our ABG paver.”
About The Author: Goodwin is a technical writer based in Des Moines, Iowa.
