Few things move slow at Infineon Raceway in California’s Sonoma County. NASCAR drivers take the 2.2-mile European-style road course’s 12 turns at speeds upwards of 150 mph. When the highly used track needs repaving, it takes fast work by a skilled crew.
Deadlines and tight schedules are nothing new to Ghilotti Construction Co., established in 1914 and owned and operated today by Richard Ghilotti and Brian Ongaro. Rick Cohn, Ghilotti paving superintendent, said that from milling to the striping, the Infineon project was a race to the finish.
“We had a 15-day window during the August dry season to complete the entire project. Out of that we had only five days to complete the paving. They raced the day after we finished paving.” From the initial profile grinding to rolling the finish required a synchronized operation that could not stop. Once the actual paving began, smoothness and rideability needs required the two Cat AP-1055B pavers to keep a steady 7-8 fpm speed until the paving was completed some 10 hours later.
No time to pit
The project called for a skilled crew of 13 people and a reliable fleet of equipment. In addition to the two pavers working in tandem, the fleet consisted of a cold planer for the profile grinding and two Cat CB-634D double-drum vibratory compactors, a Cat CB-534D double-drum vibratory compactor and a Cat PS-360B pneumatic tire roller.
“Chief among our precautions on this project was to have a backup for every machine out there,” said Damon Calegari, Ghilotti equipment manager. “Downtime was not an option.”
There also were two mechanics on site at all times—one of Ghilotti’s own technicians and a technician from their local Caterpillar dealership. Also on site was a representative from Topcon, which equipped the sensors on the electronic skis.
Ghilotti, which has worked on various projects at Infinion for the past three years, was the paving contractor of choice for track officials. “We proved our mettle over that time,” noted Calegari. “We consistently met or beat our schedules there.”
The race is on
Work began with profile grinding of the existing asphalt at an average depth of 6 in., with deeper cutouts required in places to stabilize the base and ensure smoothness. About 2,400 lineal ft of rumble strips were removed and replaced as were all edge drains. After the milling was completed, about 4,000 cu yd of fill was moved in to establish drainage along the track.
The next day, nearly 10 hours of paving ensued. All hot-mix asphalt (HMA) was elevated into the paver from a windrow. The material was delivered continuously by 28 trucks making the one-hour, 15-minute roundtrip between the hot-mix plant and racetrack.
The actual racetrack is 40-ft wide and the Extend-A-Mat 10-20B screeds on the AP-1055B pavers were extended out to 22 ft so that the two machines working side-by-side made one pass on both the leveling course and the top lift.
To ensure smoothness, the pavers were equipped with three leveling skis. Each machine was equipped with a ski with electronic sensors on the two outside edges of the asphalt track. The lead paver also was equipped with a skid ski that traveled down the middle of the racetrack.
An asphalt mix with superior adherence capabilities to withstand the pressure of high-speed race cars was needed. The 1.5-in.-thick leveling course required 1,700 tons of HMA consisting of .5-in. material mixed with AR-8000 oil. The 2-in. top lift required 5,400 tons of HMA consisting of .5-in. material mixed with a PG 76-22 oil.
Some turns on the track were superelevations of about 4%, presenting a particular challenge to the pavers.
“The stability of the rubber-track Mobil-Trac system of the AP-1055Bs really held the machine in place on those banked curves,” noted Cohn. A Cat AP-1000B rubber-tire paver was on site as the backup to the track machines.
Timing of the compaction was crucial to establishing smoothness.
“The HMA was laid down at 335°F and we needed to compact it at no less than 290°F,” said Cohn.
Two 138-hp Cat CB-634D double-drum vibratory compactors went to work on the breakdown rolling. Helpful to the timing of this project was the automatic speed control on the CB-634Ds that allowed the operator to easily match travel speeds to the vibrations per minute to better achieve proper densities with fewer passes.
A 99-hp Cat PS-360B pneumatic compactor, with its wide tires and large tire overlap, was chosen for the intermediate compaction. The PS-360B provides 2.25-in.-wide overlap of the front and rear tire paths and a broad rolling width of 90 in. It also features two speed ranges that can be shifted while propelling to aid fast, smooth travel.
A 124-hp Cat CB-534D, in static mode, rolled the finish. Final density achieved was 97.5% on average. A profilograph was run before and after paving.
“The results were an 82% improvement in smoothness,” said Cohn. “NASCAR and the super bikes love it.”