Plastic waste pollution has become a major global concern, posing serious threats both to the environment and to human health. While traditional recycling methods have their limitations, there’s a buzz about a new idea: turning plastic waste into geosynthetics. It’s a fresh take on recycling that promises a sustainable solution beyond the usual practices.

Plastic is undeniably handy in our daily lives, but its rampant use comes at a cost to sustainability. Production and disposal of plastic not only releases greenhouse gas emissions but also creates hazardous waste. To make matters worse, plastic often breaks down into tiny particles called microplastics, polluting ecosystems and harming wildlife.

Believe it or not, we are now producing twice as much plastic waste as we did 20 years ago. Unfortunately, much of it ends up in landfills, gets burned, or finds its way into the environment, with only a fraction actually getting recycled.

Most of the plastics we use today are “virgin” plastics, meaning they are made from crude oil or gas. While there has been some increase in using recycled materials, it is still just a drop in the ocean compared to total plastic production.

So, what is the solution? Enter upcycling. Instead of just recycling, upcycling involves creatively repurposing waste to give it new life and value. And one exciting application is transforming plastic waste into geosynthetics—planar products that are generally manufactured from durable polyethylene or polypropylene polymer materials and are used in soil, rock, earth, or other geotechnical engineering-related applications.

Why geosynthetics? Well, while they are often used in road construction to reinforce weak subgrades—a common headache for engineers—most geosynthetics are made from new plastics, which aren’t very sustainable or eco-friendly.

By upcycling plastic waste into sustainable geosynthetics, we could tackle two problems at once: plastic pollution and weak road foundations. 

New Process Leading to Stronger Material 

A newly developed composite geosynthetic manufacturing process utilizes advancements in material and manufacturing technology, particularly in the initial stages, to create a composite geosynthetic consisting of a geogrid made of 100 percent upcycled polypropylene bonded to a nonwoven geotextile. This process involves melting polymer beads and extruding them into a three-layered sheet with a white/black/white appearance through coextrusion. The three layers are extruded simultaneously, forming a single sheet without any joining.

Now, with regard to the practicality of using these sustainable geosynthetics in a real-world scenario, such as an unpaved road in the United States, the goal is bridging the gap between waste management and civil engineering, possibly leading to innovative solutions to meet both environmental and infrastructure challenges. It’s a story of turning trash into treasure, with potential benefits that reach far beyond just one road.

Iowa’s Groundbreaking Approach

In the heartland of America, innovation meets infrastructure as Iowa pioneers a groundbreaking approach to unpaved road stabilization. Nestled in the rural landscape, three full-scale test road sections stand as testaments to progress, each poised to redefine road construction as we know it.

At the forefront of this endeavor lies a newly developed composite geosynthetic, poised to revolutionize road stabilization. Comprising a fusion of a geogrid crafted from upcycled plastic and a nonwoven geotextile, this innovative marvel promises durability with an eco-conscious edge. 

Through rigorous testing, including exposure to real traffic loads ranging from trucks to farm equipment, the performance of these unpaved test sections was examined by an Iowa State University research team. Utilizing field tests such as the dynamic cone penetrometer (DCP) test and the lightweight deflectometer (LWD) test, the performance metrics were meticulously assessed. The DCP is a highly efficient and effective tool for testing soil strength onsite, monitoring the condition of granular layers and subgrade soils in pavement sections over time, and uses a simple, easily portable instrument. The LWD test provides rapid determination of the elastic modulus—a key factor in mechanistic pavement design—and is used to assess the overall compaction quality of pavements.

The result, unpaved roads fortified with geocomposite, emerged triumphant, showcasing a significant reduction in permanent deformation over the evaluation period. These results underscore the transformative potential of the geocomposite in enhancing road performance, paving the way for a future where durability meets sustainability on every unpaved stretch.

As the journey continues, the need for continuous monitoring and evaluation of these test sections over extended periods remains paramount. With each passing mile, the promise of a smoother, more sustainable road ahead beckons—a testament to the power of innovation in shaping the highways and byways of tomorrow.

Araz Hasheminezhad is a graduate student at Iowa State University. Araz is currently studying geotechnical engineering and will graduate in 2026.

For more information on the TR-799 project, visit: https://prosper.intrans.iastate.edu/research/in-progress/base-stabilization-of-iowa-granular-roads-using-recycled-plastics/.