If you?re a race fan, the Lowe?s Motor Speedway (LMS) in Charlotte, NC (actually Concord, NC) probably offers one of the best venues to satisfy your high-octane appetite. And if NASCAR doesn?t quite satisfy your need for speed, the new quarter mile drag strip recently constructed at the speedway facility is sure to fit the bill.
The drag racing facility opened in September with the inaugural NHRA Carolinas Nationals, round 19 of the 24-race NHRA POWERade Drag Racing Series. The dragway is located on 125 acres of LMS property across U.S. Highway 29 from the speedway and adjacent to the LMS dirt track. Initial construction began in January, including a 34,000 square-foot starting-line tower and grandstand structures that will accommodate 30,000 race fans.
The facility?s new drag racing strip, known as zMAX Dragway at Concord, pit areas and midway will cover 46.5 acres, with construction requiring moving 750,000 cubic yards of dirt, placing 65,000 tons of aggregate stone base and paving 50,000 tons of asphalt. Construction crews poured concrete for the four-lane, quarter-mile drag strip in late June. Most drag strips have concrete for the first 660 feet or less, but the transition from concrete to asphalt often upsets the traction of the rear wheels, making the car unstable for drivers as they barrel toward speeds in excess of 300 mph down the 1,320-foot track.
As the only four-lane state-of-the-art drag racing facility in the United States, the drag strip features a pair of two-lane strips located side-by-side. The design will allow racing to continue in the event of an oil-down that requires extensive cleanup to one of the lanes. An oil-down usually halts the action for extended periods and has been a major obstacle for live television coverage.
Beyond the concrete quarter-mile racing surface, only one of two concrete drag racing facilities in the NHRA POWERade Series Circuit, asphalt extends the strip another 2,680 feet. From start to finish, the racing surface is 4,000 feet long, just over three-quarters of a mile. At the end of the asphalt surface is a 200-foot long sandpit.
Paving the shut-down area
Granite began placing the binder base layers of the 2,680-foot-long shut-down lanes the third week of July, and completed its work by the end of July. The shut-down lanes extend from the quarter-mile concrete racing surface another half mile, the distance required to bring the drag racers, traveling 300-plus mph by the time they reach the asphalt, to a safe stop.
Using a Volvo PF6110 tracked paver, Granite placed the rich (5.4 percent) liquid asphalt mix design (Marshall) in three lifts: a 2-inch 19mm binder base course, a 1.5-inch 12.5mm binder course and a 1.25-inch 9.5mm surface course.
With each of the two two-lane strips measuring 60 feet wide, the paving crew staggered the lift width on each of the mats to prevent any longitudinal joints from falling directly in line with the tire travel path of race cars. On the first lift for example, the paving crew set the screed width at 15 feet, following with a 12-foot-wide pull on the second lift and a 15-foot-wide pull on the final surface course.
?We generally use a paver with an 8-foot-wide screed, but on this particular project we used one (the Volvo PF6110) with a 10-foot wide screed,? notes Stephen Cosper, owner of Granite Contracting. ?Due to the tight smoothness specs we had to hit on this job, we thought the tracked paver would provide the most stable working platform to deliver the best results. It was not only important to stagger longitudinal joints on each lift and keep them away from the travel path of the race cars, but also to keep the transition (from concrete to asphalt) of the track as well as the entire surface as smooth as possible. When a car is traveling at over 300 mph coming off the concrete surface onto the asphalt surface, you don?t want to hit any surface deviation.?