A New Road at a Good Price

By Daniel C. Brown, Contributing Editor

The Roadtec SX-7 reclaimer worked 8 inches deep and 8 feet wide.

The Utah Department of Transportation estimates that it saved more than $1.2 million with the Full Depth Reclamation (FDR) process for SR-68 near Saratoga Springs – compared to remove-and-replace reconstruction.

FDR saves money by eliminating the hauling of base materials involved in removal and replacement. Moreover, the state said it also saved approximately $1 million by not having to identify and relocate utilities under the existing roadway.

The SR-68 project included reconstruction of an existing two-lane roadway with upgraded accesses and intersections, and widening to a five-lane roadway for about 12 miles. The general contractor, Geneva Rock Products, of Orem, Utah, subcontracted the FDR portion of the project to Valentine Resurfacing, of Vancouver, Wash. Construction extended from the summer of 2008 into the fall of 2009.

Valentine used a Roadtec SX-7 reclaimer to pre-pulverize the roadway to a depth of 8 inches, working 8 feet wide. Valentine also added water to the pulverized material to attain the optimum moisture content for adequate dispersion of a solventless emulsion, which was supplied by Road Science, LLC, of Tulsa, Okla. The contractor then regraded the material to a new profile, pulverized again to add 4.5 percent of solventless emulsion, and compacted the roadway.

The stabilized base was overlaid with 5 inches of asphalt and a 1.25-inch layer of open-graded friction course. It is a 20-year design.

The FDR process for this roadway saved hauling more than 20,000 dump truck loads of excavated and imported materials, according to the state. What’s more, says Utah, the FDR option resulted in an energy savings of 37 percent compared to conventional removal and replacement – and a 19-percent reduction in carbon dioxide emissions. v

Go Green – Save Green

Full-depth reclamation rejuvenates existing materials to build a new road base.

Green, sustainable road construction is thriving in the in-place asphalt recycling world. Proving that, the full-depth reclamation (FDR) process saved approximately 80 percent of the cost of complete reconstruction of a two-lane road for Grady County, Ga. Briefly, the FDR process calls for full-depth in-place mixing and stabilization of an existing asphalt roadway.

Two reclaimers first worked one 11-foot lane and stabilized the old asphalt to a depth of 8 inches.

To reconstruct the 11.5-mile stretch of Old State Route 179 and cap it with 2 inches of hot mix asphalt would have cost more than $10 million, estimates Rusty Moye, Grady County administrator. By contrast, the FDR process – plus a 2-inch asphalt overlay – cost just $2.24 million. “It costs about $1 million per mile for complete reconstruction,” says Moye. “For that we would remove the old roadway, regrade it, put a new 8-inch base under it, and repave it.”

This is one of the longest FDR projects ever performed in Georgia. Even so, the in-place reclamation plus overlay took just 3.5 weeks, compared to three or four months that complete reconstruction would take, said David Faust, project manager for Blount Construction Co. of Marietta, Ga., the FDR contractor. Plus, FDR did not require closing the road, as reconstruction would have.

Blount’s first move in the FDR process was to spread 60 pounds of Portland cement per square yard on the original roadway. It consisted of a 1.5- to 2-inch layer of a bituminous-sand mixture placed atop a base of sandy clay. The county’s consultant, Watkins & Associates, Tifton, Ga., recommended the 60-pound rate, and the county used a state specification for the FDR work.