Foamed asphalt a good fit for U.S. 1 in Washington County
Sargent corporation crews this July completed work on two sections of Route 1 in Washington County, including 3.7 miles in the town of Whiting and 2.33 miles in the town of Pembroke. Both sections of the 3.7 million project included ditching, culvert replacement and ledge removal.
In addition, the Pembroke section included rebuilding the surfaces of the roadway using a foamed asphalt and cement application.
Operations Manager Jim Conley said it was the first time Sargent Corporation had used the foamed asphalt process, but it probably would not be the last.
“I anticipate seeing this process used more often to rehabilitate roads that are in poor condition,” he said.
The advantage of foamed asphalt process is that a stabilized base for the roadway is created using materials that are in place, as opposed to removing 24 inches of old material and placing 24 inches of new material.
The process involves grinding up the existing pavement and mixing it with the gravel underneath. Then, four inches of the reclaimed material is removed from the existing pavement area, placed on the shoulders, and compacted to finished grade.
Finally, a layer of cement is placed on the surface and the road is reclaimed a second time while injecting foamed asphalt into the mixtures of cement and reclaimed aggregates.
Once this process is completed, the crew has 24 hours or less to get the road completely fine-graded and prepped before the asphalt and cement set up and the mixture becomes too hard to fine-grade.
After fine-grading, a six-inch layer of hot bituminous pavement was placed to complete the roadway.
The Lane Construction Corporation worked with Sargent crews as a subcontractor on the foamed asphalt application.
Conley said foamed asphalt has been used sparingly in Maine, but it is fairly common in other areas of the U.S., particularly those that don’t have good aggregate sources. He said the Pembroke section of the Route 1 project had a poor quality gravel base, but years of paving and repaving had left a layer of pavement that was six inches thick. Grinding and reclaiming the pavement and mixing it with the existing gravel resulted in a substantial layer of base material.
Ledge removal on the project was challenging, because it involved removing ledge from the side of the road for safety. The ledge included some large outcrops that were very close to the edge of the road and directly beneath utility lines and the existing roadway. Sargent tried mechanical excavation first.
“It turned out to work quite well,” said Conley. The crews removed 6,800 cubic yards of ledge using a CAT 336 excavator with a 7,500 pound hoe ram and a Volvo 210 excavator with a 5,000 pound hoe ram.
The project also included 3,500 linear feet of pipe for cross culverts and driveway culverts and 36,100 linear feet of ditch excavation.
Work on the project started in late summer 2010, and the crews were able to work on ledge removal until January. The project was completed in early July 2011.
Mike Gordon was the project superintendent, Doug Morrison and Travis Fernald were the project managers, and Ken McIver and John Koch were the foremen.