The traveling speed can be slower than tire recyclers would prefer, but in several states the use of crumb rubber as an asphalt mix ingredient has been written into the specifications and has gained acceptance.
In a "Spotlight on Rubber" session at the Institute of Scrap Recycling Industries Inc. (ISRI) 2010 Annual Convention, researchers from two states and a county official from Ontario portrayed the timelines of the use of crumb rubber in pavement mixes where they live.
According to Louay Mohammad of Louisiana State University (LSU), Baton Rouge, it took more than a decade of research, testing and advocacy, but in Louisiana the market has recently blossomed.
Mohammad said LSU became involved in testing with the passage of a federal transportation bill in 1991 that required recycling. Testing continued throughout the 1990s and into this decade, and in 2007 the Louisiana Department of Transportation (LaDOT) had approved a specification for use in LaDOT projects.
In the summer of 2008, said Mohammad, the price of crude oil skyrocketed and asphalt binder became both expensive and difficult to source. "We offered an alternative-the potential to utilize crumb rubber," he commented. In October of 2008, a contractor stepped forward to use 15,000 tons of asphalt mix with crumb rubber to keep a road project alive, and since then the momentum has been positive.
"Guess what? Success breeds success," said Mohammad. "There is currently a demand for some 250,000 tons of rubberized asphalt on five projects that are underway in Louisiana. He said the cost savings have become clear "and not it's something natural that our state is using."
Mohammad urged attendees to patiently conduct field tests and have specs ready to go for rubberized asphalt. "We had the data to present when the opportunity presented itself," he remarked.
In Grey County, Ontario, Gary Shaw of the county's Transportation & Public Safety Department championed the use of rubberized asphalt partly in response to a tire dumping and stockpiling problem.
He said lobbying and continual testing worked in combination to ease the fears of county officials and contractors, who have subsequently found that rubberized asphalt is providing performance advantages such as resistance to cracking and fading.
In South Carolina, Serji Amirkhanian of Clemson University has been helping that state's tire recyclers research and test rubberized asphalts for two decades.
Testing has shown that rubberized asphalt can last longer than conventional mixes in part because of its resistance to cracking and rutting. Even when the process adds costs up front, the life cycle cost for the material offers savings, said Amirkhanian.
Before the Spotlight session, long-time tire recycler Jerry Swensen of Auburndale Tire Recycling in Wisconsin was honored with a "Service to Industry" award. Swenson said he appreciated the award and wasn't expecting it, and that he put 20 years of his life into tire recycling "because I believe in it."
The 2010 ISRI Annual Convention was held May 4-8 at the San Diego Convention Center.
Article excerpted from "Recycling Today, www.isri.org,