Turning Tires Into Roads

PROFESSOR AWARDED $300,000 TO RESEARCH “GREEN” MATERIAL

Georgia Southern University civil engineering professor Junan Shen has been awarded nearly $300,000 from the Georgia Department of Transportation (GDOT) to conduct the second phase of his research project testing the durability of rubberized asphalt mix on Georgia’s highways and interstates. Shen is researching whether crumb rubber — derived from scrap tires — is a viable alternative for building roads.

“This is an environmental project as well because crumb rubber is produced from some of the nine million scrap tires that accumulate in Georgia every year,” Shen said. As the professor explained it, “the crumb rubber modified paving mixture would benefit the state’s treasury and environment because it costs less to produce than conventional SBS modified asphalt, and it uses thousands of old tires that would otherwise be buried in landfills.”

During the two-year project, Shen, his research associate Zhaoxing Xie and several undergraduate civil engineering students will conduct a series of laboratory tests to examine the mechanical properties of the “green” rubberized asphalt mixtures produced via two processes — dry and wet. In the dry process, small particles of crumb rubber, rock and asphalt cement are blended together at the same time, however, in the wet process the crumb rubber is mixed with the liquid asphalt first and the rock is then added to create the final mixture.

The study will evaluate the mixtures’ performance properties such as the rutting and anti-stripping properties, and researchers will subject the materials to an accelerated weathering test to see how they survive weather aging. Students will contribute to the research by preparing the samples and conducting the testing. “By involving students in the project, they will gain additional knowledge, experience and skills to better prepare them for careers in Georgia industries,” Shen said.

The interaction of crumb rubber with asphalt binders will be examined at a microscopic level using advanced laboratory equipment such as Scanning Electron Microscopy and Gel Permeation Chromatography. The research team will then study the rheological (flow) behaviors of the asphalt binders modified with crumb rubber by using Georgia Southern’s new Dynamic Shear Rheometer and Bending Beam Rheometer, which were purchased recently for the University’s advanced Asphalt Laboratory within the Allen E. Paulson College of Engineering and Information Technology. This new lab will provide research services to a variety of state and private companies, including the GDOT, and will help faculty members expand their research and collaborate with other researchers around the country. Shen, who is also the lab’s director, said the laboratory will allow his team to conduct cutting-edge research on improved asphalt mixtures and asphalt pavement-related research.

– Sandra Bennett