Asphalt Recycling Section
A New Road at a Good Price
By Daniel C. Brown, Contributing Editor
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.
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.”
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