Georgia Southern University has been selected by the Georgia Department of Transportation (GDOT) to conduct the second phase of a major project.
Georgia Southern University associate professor of civil engineering, Junan Shen, Ph.D., along with his research associate, Zhaoxing Xie, Ph.D., and up to four Georgia Southern undergraduate civil engineering students, have been chosen to investigate the performance of rubberized asphalt mix for use in road construction in Georgia.
The second phase of the nearly $300,000 research project will examine how "green" material derived from scrap tires will make a viable alternative for use in road construction. The project has been a two-year study to determine how to make a durable, energy-saving, green pavement using "crumb" rubber.
Shen completed the first phase of the project by examining the long-term performance of three roadway sections: I-75 near Valdosta, Ga.; I-75 near Perry, Ga.; and I-20 in Augusta, Ga. in December 2012. Each of these sections of interstate was paved with open-graded friction course (OGFC) and stone matrix asphalt (SMA) underlying the OGFC. Test sections were visually inspected for surface distress following the guidelines in GDOT's Pavement Condition Evaluation System (PACES) manual. Core samples taken from the test sections were evaluated in the laboratory on selected physical properties, including durability.
The objective of the second phase, two-year study project, is to make durable, economical and green asphalt mixtures containing crumb rubber. Shen and the students will examine the mechanism of rubberized asphalt mixtures produced via the "dry process" and "wet process" through a series of laboratory tests. The interaction of crumb rubber with asphalt binders will be examined at a microscopic level using advanced laboratory equipment such as Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy and Gel Permeation Chromatography.
The team will then study the 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 recently purchased for the University's Asphalt Laboratory. They will design rubberized asphalt mixtures and subject the material to an accelerated weathering test and evaluate other performance properties such as the rutting and anti-stripping properties of the designed mixtures.
Lastly, a comprehensive comparison of the mixtures designed with crumb rubber will be conducted based on both the laboratory and the field performance obtained through the team's study. Then, the Georgia Southern researchers will provide the GDOT with recommendations for building durable, economical and green rubberized pavements.
"The potential cost savings and ultimately the environmental impact could be tremendous for the state of Georgia," said Shen. "Georgia Southern has made a significant investment to establish a new Asphalt Laboratory, and we are excited about the services that we are now able to provide to the paving industry and government agencies."