Cold-in-place recycling has been used for years now on transportation projects across the country. The process entails using a train of equipment to convert previously-used materials into the foundation layer, all without removing, transporting, heating, or storing tons of asphalt. This technique saves time, money and the environmental impact of road projects large and small.
Now, RS&H has used the cold-in-place construction method for the first time on an airfield in Georgia, repaving Runway 16/34 at McKinnon St. Simons Island Airport. The airport was chosen by state officials to showcase the new, green method of aviation paving.
Consider the St. Simons airport as an early adopter. In the future, more general aviation facilities throughout the state may utilize the same cold-in-place method.
“It was a perfect solution,” said Brian Thompson, an RS&H senior aviation engineer who served as project manager. “Not only did cold-in-place recycling help us work within a tight budget and timeframe, but it also limited the amount of truck traffic coming onto the island. On a small resort island, those extra trucks would have had a significant impact.”
Three Projects in One
Repaving the runway was just on part of a three-contract airfield rehabilitation program. Projects included rehabilitation of the runway pavement; new runway and taxiway marker lighting; partial rehabilitation of the shoulder pavement; new lighted airfield and directional signage; a new precision path approach indicator (PAPI) guidance system, and a new supplemental wind cone. Numerous electrical upgrades, including new cabling and conduit, were also installed.
Construction began in September as the three contracts were initiated concurrently to avoid multiple closures of the runway. The airport’s primary runway, 4/22, remained in service while construction was underway, and traffic was not interrupted.
In total, the rehabilitation of the runway pavement covered the equivalent of a 12-foot roadway width to a length of 5.4 miles.
RS&H provided engineering, design, and construction administration/testing services for all projects. Seaboard Construction Company of Brunswick, Ga., was the general contractor for the pavement rehabilitation work. Trinity Electrical Services of Baxley, Ga., was the general contractor for the two electrical contracts.
How Cold-in-place Recycling Works
In this process, existing asphalt is milled, mixed with an un-heated asphalt emulsion and a small amount of Portland cement. The resulting mixture is placed with a conventional asphalt paving machine and rolled in place as a pavement base course.
A conventional bituminous surface course is placed on the recycled base material to provide a smooth finished surface. The pavement milling, addition of asphalt emulsion and cement, mixing, and base course placement occurs in a single equipment train.
Cold-in-place recycling avoids the effort and costs of removing the existing worn out asphalt, hauling those materials off site, and importing and placing new materials. Hundreds of truck trips are avoided, which would otherwise clog local roadways. Cold-in-place recycling avoids the cost and emissions generated in heating bituminous materials for paving, and because it dramatically reduces the emissions, noise and traffic congestion associated with trucking materials is also eliminated.
Thompson notes that, while there are a number of green advantages, the process also makes projects more cost effective.
“It’s a method that more general aviation airports can benefit from,” he said.