Cat AP600D Asphalt Paver ready for takeoff when opportunity arises
- 17 March 2011
- Company & Industry News
Peab Asfalt of Sweden primarily handles major road and highway projects in the inland portion of the country. But the company was willing and able to take on a new challenge when an airport runway needed to be paved in their own backyard.
"When you're working on a project like this, anything can happen," said Reijo Seppanen, project superintendent for the company. "You can have problems with the weather and there are always time pressures, deadlines to meet. We have to get off the runway one hour before the next airplane is arriving."
The work was done at an airport in Jonkoping. It's a relatively small airport but still crucial to the inland area of Sweden. "We don't have many airports around here," Seppanen said.
Flights typically were rerouted during the project, with the exception of two per day in the later afternoon or evening. That enabled Peab Asfalt to make progress almost daily, and also kept outbound and inbound passengers and freight connecting to key hubs in Stockholm and Copenhagen.
"Even with the limited flights, we had to adjust paving schedules," Seppanen said. Paving often started in the middle of the night and extended into the late afternoon of the following day.
Another contractor handled the first phase of the project, which consisted of milling about 50 mm (2") off the existing surface. "Then we put the asphalt down," Seppanen said.
The paving portion of the project took about three weeks.
Segregation is always on the mind of Seppanen and others at Peab Asfalt. The efforts start at the plant, with proper loading of the trucks. The trucks themselves have rounded, not flat, bed bottoms. This prevents sticking when the materials are end-dumped into the Cat AP600D later in the process.
The trucks travelled about 70 km (43 miles) from the plant to the airport. Traffic was light given the area and the fact much of the paving was done at night. Shorter truck cycle times, combined with other segregation fighting efforts, paid off.
"Our trucks are insulated, so the asphalt stays hot," Seppanen said. "The asphalt is covered as well. There was no problem keeping the asphalt in the trucks hot because the job took place in the middle of the summer."
The mix left the plant at 170º-180º C (338º-356º F), and was dumped into the hopper at about 160º-165º C (320º-329º F). Plant production, paving speed and trucking were all calculated to keep the paver moving at a consistent pace. "We move continuously," Seppanen said. "That's one of the key efforts we make to prevent segregation."
Another segregation-fighting technique is allowing mix to collect in the sides of the hopper throughout the shift. "We don't close the (hopper) sides between lifts to loosen material," Seppanen said. "The asphalt on the sides is cold, and we don't want to shake it loose and mix it with the hotter material. When the work is done for the day, we clean the sides."
The AP600D was a newcomer to the site, with the company previously using a different manufacturer's product.
"I really like the Cat paver," Seppanen said. "It's silent compared to others." He also appreciated its fuel efficiency. "It doesn't take a lot of diesel–it's very stingy with the fuel," he said. Crews also found the screed adjustments easy to make.
The paver worked at a pace of about 4-5 m (13-16') per minute, placing a single lift of 40 mm (1.5"). The Cat paver worked at a width of 4.5 m (14.8'). Ten passes were required to cover the entire width of the 45 m (148') runway.
"The middle of the runway is the highest point because of drainage," Seppanen said. "We started at one side, then made five passes until we reached the middle. Then we started at the opposite side, and worked our way back to the middle."
The width of the project led to many longitudinal joints. Peab Asfalt crews placed the new, hot mat slightly higher than the adjacent cold mat. A breakdown compactor used a small side roller to compact the joint.
Three heavy rollers handled compaction. All three were in the 11 metric ton (12 short tons) range.
The first roller made 6-7 passes, with a movement up being one pass, and the movement back counted as a second pass. "The operator was very tight to the paver, and worked as far back as 20-30 m (65-98')," Seppanen said.
The second roller worked about 50 m (164') from the paver. The number of passes varied based on that day's conditions. The compactor was vibrating while making its passes.
The third roller had no set distance between it and the rest of the paving train. "He mostly worked to take the tracks out of the mat and make it smooth," Seppanen said.
Core samples were taken along the way to ensure adequate compaction was being achieved.
The project had production and time demands, but Peab Asfalt was glad to take it on. "We don't have many projects like that come up," Seppanen said. "When there is an opportunity, you have to take advantage of it."
Product support is very important to the company's efforts to hit deadlines and overcome other obstacles, Seppanen said. "If we ever have a problem, I call the dealer and they help right away," he said. "We try on the phone first, and usually can solve problems that way. If that doesn't work quickly, they come to the jobsite right away."
The combination of customer support commitment and parts availability helps keep the equipment up and running. "It's important on time-sensitive jobs like this," Seppanen said.
The airport proved to be a challenge, but in this case, both crew and paver proved more than up to the task.