FDR in Tight Areas

By Lisa Cleaver, editor
Created: January 10, 2012

Overcoming several challenges, Ruston Paving uses full depth reclamation and soil stabilization with Portland cement on a parking lot project in Upstate New York.

Parking lots pose a challenge for FDR projects because of the size of the work area versus the equipment size.
Parking lots pose a challenge for FDR projects because of the size of the work area versus the equipment size.
The REIT parking lot project had several challenges, but the greatest challenge was educating the client about the advantages of FDR.
The REIT parking lot project had several challenges, but the greatest challenge was educating the client about the advantages of FDR.
The entire recycled area was paved with two layers of hot mix asphalt, 3½ inches of binder and 1½ inches of top.
The entire recycled area was paved with two layers of hot mix asphalt, 3½ inches of binder and 1½ inches of top.
Ruston Paving has recently purchased more efficient equipment that is driving its efforts in expanding and doing more FDR and “green paving” work.
Ruston Paving has recently purchased more efficient equipment that is driving its efforts in expanding and doing more FDR and “green paving” work.
One challenge on the REIT project was “nasty soil and moisture problems,” says Alex Marchese, project manager for Ruston Paving.
One challenge on the REIT project was “nasty soil and moisture problems,” says Alex Marchese, project manager for Ruston Paving.

In the fall of 2009, Ruston Paving was approached by REIT Management and Research in Fairport, NY. REIT Management’s Woodcliff Office Park had a 150,000 SF deteriorating parking lot, and Ruston Paving was asked to provide options for the repair and reconstruction of the area. The project was to be phased over three years to enable the active parking lot to remain in use.

During the first phase of reconstruction in the fall of 2010, Ruston Paving was contracted to mill and replace a portion of the parking area surface, as specified by a third party engineer’s design. Once the original surface had been removed and the underlying base evaluated, it was determined that it was necessary to remove, undercut and replace large areas of subgrade and install subsurface drainage in order to stabilize the area for final surfacing.

“Once we got down to the stone subbase we found failures, 20% to 30% of the entire area had to be reconstructed,” says Alex Marchese, project manager for Ruston Paving. “This resulted in more than anticipated expenditures and extended the work schedule significantly.”

“Once we started doing the excavation and trying to remediate the core base condition, the areas with failures just kept growing and growing creating the need for deeper undercuts and drainage,” says Lang Butler, vice president with Ruston Paving.

After the expensive lesson learned from the first phase of the parking lot reconstruction, REIT Management’s engineer suggested a full depth removal and replacement of the stone base and pavement for the next phase, which was to begin in the summer of 2011.

Ruston Paving then made the recommendation to REIT to consider full depth reclamation (FDR) with a Portland cement stabilization option.

“We realized it was something we should address over the whole area instead of just isolated areas,” says Butler.

A quality fix

The FDR process reconstructs worn out asphalt pavement by recycling and modifying the existing material on site. The old asphalt and stone subbase are pulverized, blended and compacted to produce a strong, durable base for either an asphalt or concrete surface. In most cases, additives, such as Portland cement, are incorporated into the FDR process to enhance the stabilizing characteristics. FDR uses the old asphalt and base material for the new pavement. There’s no need to haul in aggregate or haul out old material for disposal. Truck traffic is reduced, and there is little or no waste.

There are many advantages of the FDR process over the traditional method of full depth reconstruction, says Tim McConnell, pavement and soil specialist with Ruston Paving.

“You can get into a lot of unknowns with full depth reconstruction,” says McConnell. “With FDR, it’s a quality fix. You can repair the entire area at one time with no guesswork. You create a uniform area to start out with for your new pavement, which is always important. And you get away from all these little patching areas.”

Repairing the entire area is one benefit of FDR; the other is the Portland cement, which helps stabilize the base and create a more uniform platform that is a more structurally competent base, says McConnell.

“Portland cement helps with moisture issues, which we had a lot of on this project,” he says. “It also strengthens the materials you have in place to create a base that’s structurally more superior to an aggregate base even if it’s on fabric.”

FDR also has the greatest bang for its buck, says Butler. “REIT was able to take advantage of a 30% to 40% cost savings while providing a better product and shortening the construction schedule on this project,” he says.

As originally specified, the entire recycled area was then paved with two layers of hot mix asphalt, 3½ inches of binder and 1½ inches of top. The final phase of the project will be completed this year, again using FDR.