C&D World: Markets Still Stirring for Recycled Aggregates

Producers of recycled aggregates who have tired of selling into fickle or skeptical markets may begin to study how Harold Green and Chamberlain Contractors, Laurel, Md., as well as paving contractors around the world, prepare foamed asphalt.

Green explained to attendees of C&D World 2009 how the production of foamed bitumen stabilized materials (foamed asphalt) can provide an ample end market for recycled aggregates.

Chamberlain currently operates two plants that make an “ambient-temperature base pavement” that the company has used on more than 800 job sites, according to Green. The technique has long been used in Germany, South Africa and other nations, he noted.

The resulting material, which Green referred to as made from “100 percent processed RAP,” can provide all but the very top (around ¾-inch) of a paved roadway.

Recycled material used in the process should include about 5 to 7 percent of fines, said Green. He also noted that a small amount of portland cement and eventually some 2 percent of turbulent “foaming” water (thus the name) must also be added.

 By Green’s calculations, recyclers who already operate a crushing plant can provide their own aggregate, pay about $1 per ton in operating costs, about $1 per ton for portland cement and $11 to $12 per ton for oil and they will have made a paving material for around $13 per ton.

When compared to a cost of from $50 to $75 per ton that contractors may pay for hot-mix asphalt, the sales potential is enormous, says Green.

In addition to being made in fixed-site plants, Green says foamed asphalt can also be made in road-portable plants that cost around $800,000 per unit.

“I feel like it’s not if but when this material becomes more accepted [in North America],” said Green of foamed asphalt’s future.

At the same session, Dennis Blanchard of Percontee Inc., Silver Spring, Md., gave an overview of how that company has been working with local paving contractors and the Maryland Department of Transportation to gain greater acceptance of recycled-content paving materials.

The company’s current plans call for it to begin making greater amounts of recycled-content paving materials at a ready-mix concrete plant that it owns but that had previously been leased by another operator.

The company has also been able to use its fines as part of an RC-6 product used in temporary parking areas and access roads.

For all such products, Blanchard is seeing a tie-in with contractors and property owners seeking maximum LEED (Leadership in Environmental Energy and Design) scores for their projects.

C&D World 2009 was held March 22-24 at the Tampa Convention Center in Tampa, Fla.