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 Zhus 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, Zhus 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
Discovering electric mobility in a playful way
18.08.2016 | Fraunhofer-Institut für Arbeitswirtschaft und Organisation IAO
Combating traffic congestion with advanced data analytics
17.08.2016 | Fraunhofer-Institut für Arbeitswirtschaft und Organisation IAO
The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.
“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...
With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.
Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...
For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.
Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...
At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.
In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...
Every three years, the plastics industry gathers at K, the international trade fair for plastics and rubber in Düsseldorf. The Fraunhofer Institute for Laser Technology ILT will also be attending again and presenting many innovative technologies, such as for joining plastics and metals using ultrashort pulse lasers. From October 19 to 26, you can find the Fraunhofer ILT at the joint Fraunhofer booth SC01 in Hall 7.
K is the world’s largest trade fair for the plastics and rubber industry. As in previous years, the organizers are expecting 3,000 exhibitors and more than...
23.09.2016 | Event News
20.09.2016 | Event News
16.09.2016 | Event News
23.09.2016 | Life Sciences
23.09.2016 | Health and Medicine
23.09.2016 | Life Sciences