Work Speeds Ahead on Replacing Century-Old Bridges With Tunnel

Bristol’s Slopes Call for Dryer Concrete

Mon June 18, 2007 - Southeast Edition
Maybelle G. Cagle



Construction equipment is temporarily replacing race cars as the main attraction at the Bristol Motor Speedway in Tennessee.

The construction is part of efforts to resurface the “World’s Fastest Half-Mile” along with some other projects. The equipment includes a specially-modified GOMACO SL-450 slope paver.

“Baker Concrete Construction out of Ohio got the contract for the job and the folks there were aware of GOMACO and their equipment since they had done work on the water drainage/runoff culverts around Los Angeles,” said Kevin Triplett, vice president of public affairs. “The basis of this machine is very similar to the one used on those jobs, but had to be modified and adapted to the job at Bristol Motor Speedway.”

Dennis Ernst, GOMACO’s service and warranty manager, said this machine’s basic design is the same that is used in canal work.

“We had the basic design, but the difference is the rail system used here in Bristol. The frame of the machine was designed to ride on top of the outside walls,” he said. “The rail system was the biggest challenge, because it had to be designed from scratch. The grade of the track is based on the slope of the machine, so it is critical that the rail system is aligned properly.”

Crews dealt with up to a 15 percent grade in the front stretch, a 50 percent grade in the turns and up to a 17 percent grade in the back stretch.

It should take 11 pours to complete the surface, Ernst said. The machine uses a finishing drum to smooth the final surface, which will be sealed with a slight burlap-drag and a light-broomed finish.

The speedway seats 160,000 and is among the top five largest permanent seating sporting facilities in the United States, according to Triplett.

Work began after the Food City 500 Nextel Cup race in March and will be finished before the Sharpie 500 on Aug. 25.

The new surface, like the old one, is concrete.

“It’s just a different makeup. Different components constitute a different mixture,” Triplett said.

The old concrete was created with greystone aggregate and natural sand pulled directly from the Nolichucky River. Its cement content was very high, Triplett said, at 600 lbs. per cubic yard.

“What we found out is that the fine aggregate — the sand — and the stone provided challenges since the material was very inconsistent due to differential in settlement in rivers,” Triplett said. “We also found that the aggregates — both fine and coarse — were extremely dirty. This caused the bond of the aggregates and the cement paste not to take place or be very poor in the areas that did bond.”

The new concrete was created with a course limestone aggregate and a fine aggregate of natural sand from a silica source. It has 500 lbs. of cement and 100 lbs. of fly ash per cubic yard. To improve bonding, the stone is being double washed. Also, chemically-entrained air is being added to encompass 4 to 6 percent of the mixture.

Initial pours broke at an average of 4,500 psi in seven days, which should improve to 5,500 to 6,000 psi in 28 days.

The track opened in 1961 and has been resurfaced before.

“In the late 1980s and the early 1990s as the tires in racing were changing and the aerodynamics of the cars were getting more and more advanced, giving the cars more downforce and making them faster, it was becoming more and more difficult for the owner of the track at that time to keep an asphalt surface down.

“Between the steep banks of our racing surface and the heat generated by the tires and the increased downforce of the cars, the track promoter was faced with patching or completely putting the new asphalt every couple of races. In 1992, tired of doing that, he had the existing surface pulled up and became the first track owner to host a NASCAR Cup event on concrete, a surface he determined would be more durable to the pounding a race car takes. It was more durable, but even concrete when put under those conditions will give up and the subsurface of our track was beginning to deteriorate. We had to make the decision to replace it.”

The project was initially scheduled for 2006, but Speedway Motorsports, which owns this facility, as well as Lowe’s Motor Speedway in Charlotte, N.C., and Las Vegas Motor Speedway, decided to wait until this year so its preferred contractors and engineers could focus on projects at the other two tracks.

All the concrete walls, outside and inside, track surface rebar and even some of the sub-surface was ripped out.

“A lot of the concrete is being auctioned off for charity or sold. The rest has either been ground up and used for some of our parking lots or used for fill in some other areas,” Triplett said.

He noted 1,815 cu. yds. (1,400 cu m) of concrete was removed from the surface of old track. Another 842 cu. yds. (650 cu m) of concrete was removed from the walls.

Triplett said 5,500 tons (5,000 t) of asphalt was removed. Approximately 38,944 sq. yds. (32,600 sq m) of dirt was removed and replaced with the new dewatering system. This was equal to 1,948 truck loads.

According to Triplett, the “new dewatering system” was a term derived by the track’s engineers and development team to refer to the procedure used in helping with drainage.

“It consists of Geotech matting [fabric] with 18 to 20 inches of No. 1 stone topped by 6 inches of No. 57 stone, which replaced the fill dirt subsurface that existed under the old track. It will give us a bigger and better drainage system,” Triplett said.

Three separate projects are actually under way at the complex. One is at the Bristol Motor Speedway, one at the adjacent Bristol Dragway and one at the entrance to the facility, adding pedestrian sidewalks along the roadway (U.S. Highway 11) that runs in front of the facility.

“Bristol Motor Speedway and Bristol Dragway are on the same piece of property, but are two completely different facilities with two completely different kinds of racing,” Triplett said.

He said Baker Construction Services of Bluff City, Tenn., did the demolition work, as it has for the speedway on nearly every demolition project in the last decade. Baker Concrete Construction out of Ohio (no relation to the Tennessee firm) is the contractor on the speedway and dragway surface project. The pedestrian enforcement project was contracted by the city (a public/private partnership with the speedway and dragway, the city and state providing portion of the funding) to Summers-Taylor, a local contractor.

“This project is challenging, because the concrete must be much drier to prevent it from running down the track surface,” said Bubba Cooper, surveyor for heavy highway division of Baker Concrete Construction. “We have replaced all of the walls except a 50 foot section at the start/finish line. The walls are difficult because they sit at such an extreme angle. We will use 15,000 [cubic] yards of concrete during the Bristol Motor Speedway project.”

Baker Concrete is working with Phillips Concrete of Johnson City, Tenn., bringing the total concrete work crew to approximately 50 people.

CEG