Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

ASU researcher puts recalled Firestone tires to good use

26.07.2002


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 New players, standardization and digitalization for more rail freight transport
16.07.2018 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)

nachricht A helping (Sens)Hand
11.04.2018 | Fraunhofer-Institut für Arbeitswirtschaft und Organisation IAO

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: Virus multiplication in 3D

Vaccinia viruses serve as a vaccine against human smallpox and as the basis of new cancer therapies. Two studies now provide fascinating insights into their unusual propagation strategy at the atomic level.

For viruses to multiply, they usually need the support of the cells they infect. In many cases, only in their host’s nucleus can they find the machines,...

Im Focus: Cheers! Maxwell's electromagnetism extended to smaller scales

More than one hundred and fifty years have passed since the publication of James Clerk Maxwell's "A Dynamical Theory of the Electromagnetic Field" (1865). What would our lives be without this publication?

It is difficult to imagine, as this treatise revolutionized our fundamental understanding of electric fields, magnetic fields, and light. The twenty original...

Im Focus: Highly charged ion paves the way towards new physics

In a joint experimental and theoretical work performed at the Heidelberg Max Planck Institute for Nuclear Physics, an international team of physicists detected for the first time an orbital crossing in the highly charged ion Pr⁹⁺. Optical spectra were recorded employing an electron beam ion trap and analysed with the aid of atomic structure calculations. A proposed nHz-wide transition has been identified and its energy was determined with high precision. Theory predicts a very high sensitivity to new physics and extremely low susceptibility to external perturbations for this “clock line” making it a unique candidate for proposed precision studies.

Laser spectroscopy of neutral atoms and singly charged ions has reached astonishing precision by merit of a chain of technological advances during the past...

Im Focus: Ultrafast stimulated emission microscopy of single nanocrystals in Science

The ability to investigate the dynamics of single particle at the nano-scale and femtosecond level remained an unfathomed dream for years. It was not until the dawn of the 21st century that nanotechnology and femtoscience gradually merged together and the first ultrafast microscopy of individual quantum dots (QDs) and molecules was accomplished.

Ultrafast microscopy studies entirely rely on detecting nanoparticles or single molecules with luminescence techniques, which require efficient emitters to...

Im Focus: How to induce magnetism in graphene

Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.

Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

Supporting structures of wind turbines contribute to wind farm blockage effect

13.12.2019 | Physics and Astronomy

Chinese team makes nanoscopy breakthrough

13.12.2019 | Physics and Astronomy

Tiny quantum sensors watch materials transform under pressure

13.12.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>