can plastic waste be used to build roads, buildings and more? stanford engineers think so

recycled glass fiber-reinforced polymer composite

In their recent studies, Stanford engineers Michael Lepech and Zhiye Li discuss the possibility of using and incorporating recycled glass fiber-reinforced polymer composite – a tensile plastic commonly used in car, boat, and plane parts – into infrastructures including public highways and buildings. This can be a game-changer in the architecture and technology industries given that less than 10 percent of the plastic waste is being recycled yearly out of the seven billion tonnes of plastic waste generated globally.

Michael Lepech says that recycling plastic waste to be used for infrastructure purposes can be considered progressive since ‘the amount of material, along with its likely uniform composition, would make recycling it into another infrastructure application significantly easier,’ he says. However, challenges can still arise and until these have been solved, improper plastic waste recycling and turning it into buildings, highways, and other types of infrastructure may be a dream yet to come true.

For instance, Zhiye Li highlights the issues concerning the economics and logistics of managing plastic waste streams from municipal solid waste. ‘Plastic waste material flow is highly variable. Its mass can change from month to month, as can the type of plastic – lots of different packaging, for example,’ she says. Without proper waste sorting systems and active upcycling innovation, transforming the reason waste piles up deems challenging especially since the materials of plastic can differ and only some can be used for specific purposes.

high-rise buildings in Dubai | image by Aleksandar Pasaric

Stanford engineers study plastic waste applications

Stanford University engineers state that there is value in upcycling plastics into infrastructure but that at the same time, it needs to achieve certain performance requirements and still maintain low environmental impacts compared to traditional construction materials. In their studies, they looked into examples where plastic waste has been used for buildings and roads including the façade panels in the San Francisco Museum of Modern Art and the pavement in a California Department of Transportation road project.

The Snohetta-designed San Francisco Museum of Modern Art underwent a facade expansion. Here, the design team employed fiberglass-reinforced plastic – the largest architectural application in the US to date according to glazing contractor Enclos – for the rippling surface of the exterior. Driving to Oroville in California, Caltrans repaved a section of Highway 162 with recycled asphalt pavement and liquid plastic made with single-use, plastic bottles in 2020. It was the first time the department paved a road using 100 percent recycled materials, according to a government report.

cars driving on urban highway in evening | image by Ruiyang Zhang

Better plastic waste sorting management is needed

These case studies fuel the studies of Michael Lepech and Zhiye Li on the future of plastic waste for future infrastructure. Zhiye Li cautions that while there are many ways to reuse plastic for various applications, not all kinds can survive long or can be integrated into the infrastructure. ‘For example, packaging consumes more than 60% of global recycled plastic but has a short lifespan. Some automotive parts can be made with recycled plastic, but they require relatively little plastic to produce,’ she says.

Still, potential advantages are noted including reduced potential for environmental emergencies such as oil spills and reduced insurance premiums.‘There is certainly an opportunity for growth by targeting markets that value environmentally friendly or sustainable products. Firms can achieve increased clarity in strategic direction when they align value chains with corporate mission, especially in the case of environmentally conscious firms,’ he says.