Transforming Plastic Waste into Road Construction Materials

Engineer Toby McCartney, while working with a charity in southern India, observed landfill workers collecting reusable items. He noticed that plastic waste was being used to fill road potholes: melted with gasoline, it hardened and effectively sealed the holes.

Upon returning to Scotland, McCartney shared his observations with friends. Gordon Reid, co-founder of MacRebur, explained that they aimed to improve the process by developing a specialized material from plastic waste for road construction. After a year of research, they successfully created pellets from a blend of industrial and consumer plastic waste, offering a sustainable alternative to traditional asphalt.

Since its launch in April 2016, MacRebur's innovative recycled plastic road material has been utilized in various locations worldwide, from Australia to Dubai, as reported by the Scottish newspaper, the Daily Record.

"Our roads span every continent," Reid states. "We've received interest from approximately 50 countries. Currently, we're in talks with a California university to construct a test road, proving our plastic material meets U.S. standards," he adds.

The Plastic and Bitumen Mixture

Reid explains that while the idea of using recycled plastic for road construction seems straightforward, it involves a sophisticated process to develop the appropriate material. "Various plastics affect bitumen differently," he notes. "An incorrect mixture can render the bitumen more fragile."

MacRebur focuses on types of waste plastic that are not easily recyclable, such as those that would typically be buried, rather than using PET bottles. Reid avoids disclosing too many specifics to protect the company's proprietary methods.

The company's plastic road materials not only help reduce landfill waste but also decrease carbon dioxide emissions by approximately 1 ton (.907 metric tons) for every ton of bitumen replaced, as stated in MacRebur's online fact sheet.

MacRebur has engineered specialized road-building plastics tailored to various climates. One variant is crafted for hot regions like the Middle East, where roads require enhanced tensile strength to withstand heat-induced deformation. Another is formulated for colder areas such as Canada or Scotland, offering flexibility to endure freeze-thaw cycles, Reid explains.

Currently, MacRebur's products can substitute 6 to 20 percent of bitumen in roads. Reid anticipates that within two years, advancements will enable their materials to replace up to 50 percent of bitumen.

Reid highlights that MacRebur's plastic road materials chemically bond with bitumen, preventing environmental contamination. "The plastic integrates with the bitumen, forming a unified hydrocarbon structure," he clarifies.

Plastic Pins

In the U.S., recycled plastic is already aiding road maintenance. Sahadat Hossain, a civil engineering professor at the University of Texas at Arlington and director of the Solid Waste Institute for Sustainability, has innovated a solution using landfill-derived plastic to stabilize unstable soil on highway slopes. His technology involves creating large plastic pins that reinforce the soil, preventing road surface failures.

Hossain states that the recycled plastic pin has proven effective as a laterally loaded pile in various highway slope stabilization projects across Texas, Iowa, and Missouri. "The Texas Department of Transportation has officially approved the recycled plastic pin for slope stabilization," he notes. Each pin can be installed in just three to four minutes, allowing an entire unstable area to be stabilized within days.

"Once installed, the pin is highly resistant to degradation, offering a durable solution for slope repair," Hossain explains.

Hossain's UTA web page highlights that each recycled pin repurposes approximately 500 plastic soda bottles. At one demonstration site, his team installed 600 pins, effectively diverting 300,000 plastic bottles from landfills.

Hossain believes China's recent ban on importing plastic waste for recycling could open doors for U.S. entrepreneurs to produce road materials. In 2016, China imported 776,000 metric tons of plastic waste from the U.S., as reported by Chemical and Engineering News.

"I am confident that recycled plastics will increasingly be used in road construction," Hossain asserts.

He emphasizes that further research is necessary to refine new techniques, including comprehensive testing and life-cycle assessments of roads incorporating plastic materials.