Tempe, Ariz. --Imagine for a moment seeing 5 million worn tires heaped up in a pile: That is roughly the number that Arizonans produce each yearone tire for every man, woman and child. How to dispose of all those used tires without causing serious environmental hazards used to have state officials scratching their heads, but one ASU researcher believes has an answer.
Civil and Environmental Engineering Assistant Professor Han Zhu says adding a small amount of the inexpensive crumb rubber to fresh concrete can improve strength and durability. Crumb rubber is the end result of grinding used tires into one-millimeter chunks. One tire produces about 10 pounds of crumb rubber and sells commercially for less than 20-cents per pound.
While Zhu is not the first researcher to experiment with adding the tire bits to Portland cement concrete or PCC, he does own rights for the first "real world" application, a section of sidewalk on the ASU Main Campus in Tempe.
"This is my baby," says Zhu of the sidewalk between the Memorial Union and the campus bookstore. He bends down to get a closer look. Black flecks of rubber sparkle in the morning sun. "I have been coming out here to examine this sidewalk for two years. Most people think I am just a guy looking for pennies," he jokes.
Zhu began to explore uses for crumb rubber in 1998 with a grant from Arizona Department of Environmental Quality. His research, however came to a screeching halt soon after because he could not find a natural environment as an experimental site, a critical step in testing new materials prior to certification.
The researcher said few people were interested in using the new material because there was no guarantee of success. As luck would have it, Zhu found a test site in his own backyard.
In February 1999, Zhu personally added 200 pounds of crumb rubber to the concrete mixture being prepared for the ASU site. He says the ratio of crumb rubber added to the mixture equated to about 8 perPage: 1 2 3 Related biology news :1
Contact: Lynette Summerill
Arizona State University
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