A team of researchers from Nova Scotia is assessing how tire-derived aggregate (TDA) can enhance the strength of soil for civil engineering projects such as bridges, buildings and highways.

“We have a lot of soft soils in Nova Scotia that you cannot readily build on because they are too weak to support infrastructure," says Dr. Hany El Naggar, associate professor with Dalhousie University's Department of Civil and Resource Engineering. "But when you use a TDA-soil mixture for the backfill, you have something that is lightweight but significantly reinforces the strength of the foundation soil. Now, you can build the structure you want on that soil, doing it economically without any risk that it will fail.”

Scrap tires are breeding grounds for mosquitoes because they pool water. Image credit: Pixabay.The TDA being tested is manufactured by Halifax C&D Recycling Ltd., which holds a contract to recycle the approximately one million tires discarded by Nova Scotians annually. El Naggar’s team will also conduct a characterization study of the recycling company’s TDA to establish product design standards, thus reinforcing the reliability of the product for use in civil engineering projects. Findings from these initiatives could be published as early as this fall.

In addition to furthering research into the use of TDA to strengthen soil for construction projects, the university’s research is an attempt to help solve environmental and health issues related to scrap tires.

“We know that discarded scrap tires are breeding grounds for mosquitoes because they pool water, and we’ve seen the dangers of that with the Zika virus,” says Jim Simmons, an environmental engineer who has been working with Halifax C&D Recycling to promote TDA. Tire fires also release pollutants into the atmosphere, he says.