A team from Michigan Tech recently traveled to Kalamazoo and Muskegon counties in Lower Michigan to conduct field research with recycled rubber materials from scrap tires. The research group was led by Zhanping You (CEE) with students Siyu Chen, Dongdong Ge, Isaac Pantti and Brock Rudlaff.
The Kalamazoo project was a result of a joint effort of the Road Commission of Kalamazoo County (RCKC), Michigan Tech and others. Joanna I. Johnson, managing director of RCKC and You jointly applied for funding through the Michigan Department of Environmental Quality’s (MDEQ) Scrap Tire Development Grant program. For the project, four test sections were contructed—hot rubber thin overlay (HRTO), conventional thin overlay, hot rubber chip seal (HRCS) and conventional chip seal.
Chip seal consists of a spray-on asphalt emulsion covered with aggregate chips, while overlay involves a new layer of an asphalt mixture on a milled surface. The experiment included the addition of scrap-tire rubber to improve the property of the asphalt mixture. This could provide a longer sustainable pavement and another application for recycled tires.
“The purpose of the project was to evaluate the new reacted and activated rubber to investigate the applicability of such rubber, mainly composed of finely grinded scrap tires,” You says. “The aim is to create more cost-effective, long-lasting, safe and environmentally friendly mixes and surface treatments,” This was the first time such a product was used in the United States according to You.
He says preliminary results, on a three-mile test section, show HRTO provided a smoother and quieter surface compared with a traditional overlay. The HRCS posed challenges to properly applying the material at the beginning of the project.
The Muskegon County project included emulsified rubber asphalt chip seal and conventional chip seal for a county road. Again, the work was funded by the Scrap Tire Development Grant program. Paul Bouman, highway engineer with the Muskegon County Road Commission, has worked closely with Michigan Tech researchers over the years and helped identify the test sections.
You says, “the bond strength between the chip seals and the old pavement will be evaluated under various temperature and freeze-thaw conditions. Samples from these field projects will be tested in asphalt materials laboratories at Michigan Tech, in order to better understand the road performance with these rubber materials.”
Zhanping You (CEE) is the principal investigator on a project that has received a $75,000 research and development grant from the Dickinson County Road Commission. Qingli Dai (CEE) and Siyu Chen are Co-PIs on the project “Using Rubberized Overlay to Maintain High Volume Traffic Road in Dickinson.” This is a 15-month project.