Featured Research

from universities, journals, and other organizations

Arizona State University Research Finds Recycling Cure For Used Tires

Date:
September 13, 2001
Source:
Arizona State University
Summary:
Imagine for a moment seeing 5 million worn tires heaped up in a pile: That is roughly the number that Arizonans produce each year–one 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.

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 year–one 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 percent of the cement weight.

Prior to Zhu's research, similar lab studies were not encouraging for the waste product. Earlier research showed that adding crumb rubber to concrete would lower the overall compressive strength, the major criterion used in designing PCC.

Contrary to earlier research, Zhu's study showed adding the crumb rubber into PCC actually produced several benefits that would compensate for the loss in compressive strength, particularly for projects that are not considered loadbearing. These benefits include reductions in thermal expansion, also known in Arizona as Summer Fatigue, along with reductions in drying shrinkage and brittleness. The recycled rubber also shows promise in ending the crumbling associated with freeze and thaw damage in colder climates.

Zhu says these benefits alone significantly improve the overall durability and serviceability of PCC. More recently, the researcher made new advances in restoring the compressive strength level of crumb rubber PCC to specifications by simply adding a small amount of gypsum to the mix. Grounds Construction Supervisor Andy Castillo said from his own observations of the ASU project, the crumb rubber PCC appeared to avoid cracking better than its original counterpart. 'I'd be willing to use it again in another campus project," he said.

According to the Arizona Cement Association, within the Phoenix metro area, some 12,000 cubic-yards of PCC are produced each day. By conservative estimates, if just 20 pounds of crumb rubber per cubic yard of fresh PCC were added, all 5 million scrap tires produced annually statewide could be recycled into stronger and more pliable PCC for use in sidewalks, parking lots and concrete floors. This past May, Arizona Department of Transportation used the new PCC technology to constructed a 12-foot by 12-foot parking lot at its Phoenix Division site using 50-pounds of crumb rubber per fresh cubic feet of PCC. Quality monitoring is still in progress, but Zhu says, so far so good.

"It appears crumb rubber deserves public attention and more crumb rubber PCC structures should be built. This way, time and nature can help determine additional benefits this technology can bring to our communities," Zhu said.


Story Source:

The above story is based on materials provided by Arizona State University. Note: Materials may be edited for content and length.


Cite This Page:

Arizona State University. "Arizona State University Research Finds Recycling Cure For Used Tires." ScienceDaily. ScienceDaily, 13 September 2001. <www.sciencedaily.com/releases/2001/09/010913074634.htm>.
Arizona State University. (2001, September 13). Arizona State University Research Finds Recycling Cure For Used Tires. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2001/09/010913074634.htm
Arizona State University. "Arizona State University Research Finds Recycling Cure For Used Tires." ScienceDaily. www.sciencedaily.com/releases/2001/09/010913074634.htm (accessed July 23, 2014).

Share This




More Matter & Energy News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com
Boeing Ups Outlook on 52% Profit Jump

Boeing Ups Outlook on 52% Profit Jump

Reuters - Business Video Online (July 23, 2014) Commercial aircraft deliveries rose seven percent at Boeing, prompting the aerospace company to boost full-year profit guidance- though quarterly revenues missed analyst estimates. Bobbi Rebell reports. Video provided by Reuters
Powered by NewsLook.com
Europe's Car Market on the Rebound?

Europe's Car Market on the Rebound?

Reuters - Business Video Online (July 23, 2014) Daimler kicks off a round of second-quarter earnings results from Europe's top carmakers with a healthy set of numbers - prompting hopes that stronger sales in Europe will counter weakness in emerging markets. Hayley Platt reports. Video provided by Reuters
Powered by NewsLook.com
9/11 Commission Members Warn of Terror "fatigue" Among American Public

9/11 Commission Members Warn of Terror "fatigue" Among American Public

Reuters - US Online Video (July 22, 2014) Ten years after releasing its initial report, members of the 9/11 Commission warn of the "waning sense of urgency" in combating terrorists attacks. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins