When pavement on an airport starts to deteriorate, the effects can be seen on the surface. But as any New Englander can attest to, especially during spring pothole season—pavement failure isn’t just visible. Frost heaves and subsurface weakening can create bumps and cracks that make the damage felt beneath the asphalt surface. In all pavement design, the gravel beneath asphalt and concrete are just as important as the top pavement layer and a costly part of the overall system.
In 2023, the Town of Lincoln – in cooperation with the Maine Department of Transportation (MaineDOT) and Federal Aviation Administration (FAA) – decided to rehabilitate the existing aircraft parking ramp which had seen over 30 years of continual use.
Hoyle Tanner decided to reuse the gravel beneath the asphalt to avoid massive excavation and material trucking. To confirm if the materials would be suitable for a full depth reclamation
(FDR) operation, we ordered specialized tests and analyzed samples both in the field and the laboratory. The favorable results allowed Hoyle Tanner to change the reconstruction method from typical material stripping, deep excavation, and importing manufactured crushed aggregate to a process using a reclaimer. This machine pulverized the full thickness of the asphalt pavement along with a portion of the underlying materials. After pulverizing, they trimmed the reclaimed materials to the final grade, compacted them, and paved new bituminous asphalt over the top. Our design decision not only reduced the cost of the project, but through extensive testing and the re-use of onsite material, prevented the need to remove thousands of cubic yards of asphalt and gravel and the import of replacement crushed aggregate. This saved the Town and contractor over 120 truckloads of material transport to and from the airport reducing fuel consumption, noise, and air emissions; a sustainable type of design that the Town of Lincoln, Maine DOT, and FAA emphasizes because of its importance.
Hoyle Tanner was able to deliver the design through careful material testing, cost-benefit analysis, and alternative design methods.
The technical aspects of the project included testing for sub-surface material strength, gradation tolerances, and moisture and asphalt content percentages. The grading design was then modified to account for the predicted material density change, and to reshape the site to accommodate the re-use of all the material.
Our team continues to assist clients in their mission to reduce carbon footprints by utilizing alternative design methods wherever material specifications and project requirements can align. Contact Chris Singer, one of the airport engineers for this project, for more information on how we can assist.
