Stanford University has published new research exploring the use of plastic waste in constructing roads and buildings. The research project, funded by the National Academies of Sciences, Engineering, and Medicine (NASEM), identified that recycled glass fiber-reinforced polymer composite – a tensile plastic used extensively in car, boat, and plane parts – shows potential for repurposing in building applications.

The team, led by Stanford engineers Zhiye Li and Michael Lepech, incorporated computer modeling, scientific research, field data, and stakeholder interviews in their research, which was recently published in a white paper. They studied real-world applications such as the utilization of plastic waste for façade panels in the San Francisco Museum of Modern Art and pavement in a California Department of Transportation road project.

The research highlighted significant challenges in existing plastic recycling systems, particularly the complex economics and logistics involved in managing highly variable plastic waste streams from municipal solid waste. As a mitigating factor, the research emphasized the potential benefits of recycling entire buildings made of polymer composites after their useful lifespan, which could create more predictable and uniform waste streams.

Among the recommendations proposed in the white paper are improved waste sorting, encouragement of plastic upcycling innovation, a performance database of certain plastic blends, and the establishment of models to predict these materials' durability under different conditions.

The potential benefits of this form of plastic recycling extend beyond the environmental, according to the team. Businesses involved in a circular economy value chain could see advantages, including regulatory incentives, improved operational efficiencies, risk management benefits, and potential growth in markets that prioritize sustainability.

“Upcycling of recycled plastics in infrastructure sets an example of creating value by creating demand,” Li explained in an internal Stanford interview. “The recycled plastic blended construction material needs to achieve certain performance requirements and maintain lower environmental impacts than conventional construction materials.”

“Our paper shows that for a use case that has a longer lifespan – such as certain blended plastic composite building panels or asphalt pavement, the needed quality and sustainability requirements are more achievable,” Li added.