Commodities

The Environmental Protection Agency (EPA) has set a goal to increase the national recycling rate from 30 to 35 percent by 2008. To reach that goal, recyclers are going to have to start looking to alternative outlets for recyclables and expand recycling of materials like construction and demolition debris, tires and industrial byproducts, according to Patricia Martinek of the Colorado Department of Transportation (DOT), who addressed attendees of a panel discussion entitled "Alternative Markets for Traditional Recyclable Materials," at the National Recycling Coalition (NRC) Congress & Expo held in Denver.

During her presentation, Martinek discussed a research project undertaken by the Colorado DOT that examined recycling possibilities for concrete and asphalt and reuse opportunities for those materials in road building and highway applications.

In the course of research, Martinek said the DOT found the state of Colorado used 290,068 tons of concrete in 2007 and recycled only 1,100 tons. The state used 260,125 tons of asphalt and recycled 45,000 tons. "We asked ourselves, ‘Can we do better?’" Martinek said.

The report found that several states allow for the use of recycled asphalt pavement (RAP) in the production of new asphalt, including the California Department of Transportation, which allows 25 to 50 percent RAP in hot mix designs. Martinek reported similar findings for other materials, including recycled concrete aggregate (RCA) and tires, adding that Colorado Springs, Colo., has initiated a test of rubberized asphalt on local streets, using 6,200 tons in 2006.

Rick Givan of the Recycled Materials Co., Arvada, Colo., discussed two case studies that described how his company used recycled asphalt and concrete in road applications. "Sustainability is our guiding principle," Givan said. "We aim to elevate the use of the material and bring it to its best use."

Givan described the demolition of the Stapleton International Airport in Denver, a 5,000-acre commercial airport with more than 1,000 acres of paved hardscape. The company recycled 6.5 million tons of concrete and asphalt and reused one-third of the recycled aggregate on the project, Givan said.

He also discussed a current project—the demolition of the former El Toro Marine Air Corps Station in Irvine, Calif. Givan said the project will yield 4 million tons of concrete and asphalt. Furthermore, 100 percent of the material will be reused onsite, he added. "Every single ton removed on the site will be reused on the site," Givan said.

Steve Hamilton of Smurfit-Stone Container Corp. also addressed attendees about recycling opportunities for industrial byproducts, such as waste water treatment plant residues.

Hamilton said primary solids like wood fiber and secondary solids like microbial biomass generated by industrial processes can be burned as fuel, although BTU values vary with content.

He said waste water treatment residues also have land applications as soil conditioner and fertilizer.

The NRC Congress was held Sept. 16-19 in Denver. Additional information about the event, including speakers’ presentations, is available online at www.nrc-recycle.org.

Research Group Offers Returned Concrete Recycling Guidelines

The RMC Research & Education Foundation has released a new study entitled "Crushed Returned Concrete as Aggregates for New Concrete."

The study is based on research performed at the National Ready Mixed Concrete Association’s (NRMCA) Research Laboratory in Silver Spring, Md. The report "evaluates the effects of the use of crushed concrete aggregate (CCA) on fresh and hardened concrete properties by comparing these properties to concretes containing virgin aggregates," says a news release from the organization. "The report includes guidance for ready mixed concrete producers on a methodology for the appropriate use of crushed concrete aggregates (CCA) in concrete."

The ready mixed concrete industry could save approximately $300 million per year through the use of crushed returned concrete as aggregates, according to the study. "Use of CCA supports sustainable construction initiatives and adds to the benefits that concrete can provide in this arena," the NRMCA states.

"The call for increased recycling efforts for all industries is louder than ever," says RMC Research & Education Foundation Chairman Dominique Calabrese. "The study’s findings show us how we can increase recycling, while saving on both materials and disposal costs. The construction community has an obligation to examine ways to contribute to national sustainability efforts, and the CCA report demonstrates another win-win way to become more green."

Adds Foundation Executive Director Julie Garbini, "The CCA report shows how crushed returned concrete can be successfully reused in concrete for a variety of applications, while still meeting the needed performance requirements and producing a quality product. It will go a long way toward increasing the acceptance of CCA in concrete so that the industry can use this sustainable solution."

The full study can be downloaded from the foundation’s Web site at www.rmc-foundation.org.