When designing roadways, it’s often difficult to find environmentally sustainable alternatives; especially ones that don’t add to project costs. That’s why it’s exciting to see some of the creative sustainable design solutions that states are implementing. The Indiana Department of Transportation is starting to take rubber tires, which normally would have been destined for landfills, and incorporating them into roadway construction materials. This has proven to be a low-cost, green alternative to more conventional construction materials for transportation projects. Thus, saving a substantial amount of money and reducing a significant amount of waste.

Civil engineers at Purdue University came up with a mixture of tire shreds and sand, enabling Indiana to save approximately $1.2-million in project costs and rescue 1.1-million tires from taking up landfill space throughout the past two years. The material is also easier to compact, saving construction time and money.

There is another source of cost savings, outside of the projects themselves. Since landfill costs are significant, a project that uses this tire shred-sand mixture will also save municipalities money by not having to accommodate tires in landfills, doubling overall cost savings.

The mixture can also be designed to meet a variety of construction needs, including a lightweight design to support roadways or bridge abutments over soft or weak soil, stabilize slopes prone to landslides, or used as backfill behind retaining walls. Cost of the tire shred-sand mixture can be as much as 85 percent less compared to the cost of typical light-weight fill.

In February, construction related aspects of the research were presented during the International Symposium on Testing and Specification of Recycled Materials in Baltimore. The research paper was written by Associate Professor Monica Prezzi, Purdue University, School of Civil Engineering, and INDOT engineers Malek Smadi and Nayyar Zia Siddiki.