WASHINGTON - After years of growth, scrap tire recycling has hit a plateau, according to the Scrap Tire Management Council. But there is enough interest in scrap rubber to justify continued optimism, STMC officials said at the Rubber Manufacturers Association Environmental, Safety and Health Conference, May 14-15, at Miami University in Oxford.
In 1990 - the year the STMC was founded - 11 percent of scrap tires were earmarked for use, according to Executive Director Michael H. Blumenthal.
Last year, 69 percent of the 253 million scrap tires generated in the U.S. found use in one of three markets - tire-derived fuel, ground rubber and civil engineering.
The STMC's goal is to create a 100-110 percent demand for each year's scrap tires. But that goal may take longer to reach than the council first assumed.
``The good news is that we have three major markets for scrap tires,'' Mr. Blumenthal said. ``The bad news is that all three markets took a beating in the last several months.''
Ground rubber purveyors never got the boost they expected from the Intermodal Surface Transportation Efficiency Act of 1991, which was to require increasing amounts of rubberized asphalt procurement by state highway departments. That provision was never implemented and later repealed, Mr. Blumenthal said.
Last year scrap rubber was in strong demand for civil engineering applications, mostly as filler in highway embankments. That demand ended in January when two separate tire-filled embankments in Washington state caught fire.
``The Federal Highway Administration has put a de facto moratorium on scrap rubber for civil engineering in most states,'' Mr. Blumenthal said. ``This is a major blow to the industry which will take years to overcome."
Whereas 12 million to 15 million scrap tires were used in civil engineering last year, he said, the industry will be lucky to sell 3 million to 5 million this year.
Even tire-derived fuel, which is still going strong, faces a potential problem with concerns about zinc content, particularly in pulp and paper boilers where TDF is often used. The STMC is working with the ACS Rubber Division and the American Society for TEsting and Materials to quantify TDF zinc emissions, Mr. Blumenthal said.
Meanwhile, automakers are issuing mandates to rubber product makers to include ever-increasing amounts of recycled material in new products, said STMC Chairman John Serumgard.
Loose rubber fill for playgrounds and a Malaysian company's technique for "devulcanizing" scrap rubber also sho promose, although it is too soon to tell how big their markets will be, he said.