Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


ASU researcher puts recalled Firestone tires to good use


New field studies produce environment-friendly results

An Arizona State University researcher is making good use of some of the 14 million Firestone tires that were recalled two years ago. The tires were used on Ford Explorers and recalled after reports of tread separation. How to dispose of all those used tires without causing serious environmental hazards once had state officials scratching their heads, but Civil and Environmental Engineering Professor Han Zhu believes has the answer. 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 -- the technology has been around for 30 years -- he does own rights for the first "real world" application. A patent is pending on the ASU process for making rubberized concrete.

Arizona is one of the leading states for using crumb rubber in pavement, said Zhu. He 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.

While rubberized asphalt has been used for decades on roadways, rubberized concrete is a technology infant. The researcher said in the beginning few people were interested in using a new material because there was no guarantee of success.

In February 1999, Zhu personally added 200 pounds of crumb rubber to the concrete mixture being prepared for a test site on the campus of Arizona State University in Tempe. He says the ratio of crumb rubber added to the mixture equated to about 8 percent of the cement weight. Since that time, dozens of residential and commercial rubberized concrete sites have been poured, monitored and deemed successful, including some extreme cold weather applications. A field demonstration project using the recalled Firestone tires was poured last fall as part of a frontage road along Interstate 17, near Cordes Junction, Arizona. Crumb rubber concrete is also being tested for noise control along a busy freeway in Scottsdale, Arizona.

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 compressive strength, the major criterion used in designing PCC.

However, 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 by boosting the compressive strength levels of crumb rubber PCC to specifications by simply adding a small amount of gypsum to the mix.

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 in Arizona could be recycled into stronger and more pliable PCC for use in sidewalks, parking lots and concrete floors. Crumb rubber concrete appears to avoid cracking and flaking common to traditional concrete.

"Scrap rubber is a wonderful building tool that deserves public attention. As more crumb rubber PCC structures are built, the benefits that this technology can bring to our communities will become increasingly apparent," Zhu said.

Lynette Summerill | EurekAlert

More articles from Transportation and Logistics:

nachricht Study sets new distance record for medical drone transport
13.09.2017 | Johns Hopkins Medicine

nachricht Researchers 'count cars' -- literally -- to find a better way to control heavy traffic
10.08.2017 | Florida Atlantic University

All articles from Transportation and Logistics >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Wandering greenhouse gas

16.03.2018 | Earth Sciences

'Frequency combs' ID chemicals within the mid-infrared spectral region

16.03.2018 | Physics and Astronomy

Biologists unravel another mystery of what makes DNA go 'loopy'

16.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>