HILTON HEAD ISLAND, S.C.Between devulcanization, rubberized asphalt and fine-mesh rubber powders, rubber recycling was a prominent theme at the 29th annual Clemson University Tire Industry Conference.
Rubber devulcanization was far from Mark Weih's mind when he accepted the job of executive vice pres-ident at Terramix S.A., a San Jose, Costa Rica-based manufacturer of rubber gaskets for potable water pipe systems.
Terramix makes 250,000 gaskets a day, Mr. Weih said, and the factory scrap amounts to thousands of pounds a day. In 2008, Brad Corbett Sr., Mr. Weih's late boss, calculated the scrap was costing Terramix $10 million a year and ordered Mr. Weih to find a way to reuse itwith nothing going to the landfill.
After I picked myself off the floor, I set myself to dealing with 20 tons of scrap rubber every 11/2 to two days, he said.
After investigating various recycling techniques, Mr. Weih determined that devulcanization was the best choice for maximizing the value of recycled scrap.
There are a lot of devulcanization technologies, but very few people are doing it commercially, he said. On the other hand, devulcanization allows use of higher percentages of rubber scrap, and even complete replacement of virgin rubber.
Beginning as Costa Rica's only producer of ground rubber for athletic fields, Terramix progressed to a proprietary, thermomechanical devulcanization process, according to Mr. Weih.
Terramix's studies of the use of its devulcanized scrap in tire tread applications have been very promising, he said.
For example, tests showed that an agricultural tire tread can maintain 90 percent of its physical properties using 10-percent devulcanized natural rubber, saving 7 percent of the cost of manufacturing a conventional ag tire. Similar results were achieved with devulcanized synthetic rubbers, he said.
Among other things, Terramix plans to evaluate higher loadings of devulcanized styrene-butadiene rubber in tire tread compounds, and also to work in conjunction with a tire company to make its tests more relevant to the tire industry, Mr. Weih said.
Encouraged by the success of rubberized asphalt use in other states, the Asphalt Rubber Technology Service (ARTS) at Clemson University has been working with South Carolina government agencies to increase the acceptance of rubber-modified paving materials within the state, according to ARTS Director Punith V. Shivaprasad.
Thirty percent of all the asphalt used in California must contain rubber, Mr. Shivaprasad said. Arizona, Texas and Florida also use rubberized asphalt extensively, while Washington, Colorado and Georgia are evaluating the material, he said.
ARTS promotes the practical utilization of waste tire rubber within asphalt and civil engineering applications, Mr. Shivaprasad said. It sponsors the Tire Recycling Education and Development Service (TREADS) program, which provides grants for education and technology transfer. TREADS promotes applications such as rubberized concrete sound barriers and sports and playground surfaces, as well as rubberized asphalt and civil engineering projects.
As part of the end of life of scrap tires, ARTS is conducting events for tire manufacturers and tire processors to promote and update the latest developments in the civil engineering industry using scrap tires, he said.
ARTS also helped host several waste tire processors' meetings in South Carolina. It conducted a Green Roadways workshop to educate government officials and non-profits about the use of recycled materials in infrastructure projects and is working with a private company to promote the use of rubberized surfaces in parking facilities on the Clemson campus, he said.
Ontario, Calif.-based reRubber L.L.C. is still a small company, recycling only about 1 million tires annually, according to President and CEO JD Wang. But the company has big plans for its fine-mesh rubber powder business, including the opening of plants in northern China and Taiwan by year-end, he said.
reRubber uses an ambient grinding technique to make crumb rubber from 100-percent California scrap truck tires, according to Mr. Wang. The product ranges from 6 mesh, or playground size, to -200 mesh.
The company is chemistry focused, requiring partnership and testing with customers to integrated new and recycled rubber content, Mr. Wang said.
We're getting it fine enough where it bonds in different matrices with other chemicals.
For a small company, reRubber has a wide product portfolio, Mr. Wang noted. Its products include tire sealants and coatings for automotive, infrastructure and green building applications.
An insulated concrete house in California's wine country that used reRubber coatings won a prize for its innovative design, he said.
The company also does plastics and rubber compounding that has resulted, among other things, in the first 100-percent recycled-content trash can in the world, Mr. Wang added.