Millions of printed circuit boards from discarded electronics are tossed into landfills every year. In addition to the volume of waste, the material can leach chemicals into the soil. As an alternative, researchers at Shanghai Jiao Tong University in China are finding various ways to reuse the panels, including as an additive in asphalt.
Xu Zhenming and his colleagues stripped the boards of all components, pulverized the remains into a powder and used an electrostatic separator to remove fine bits of any remaining metals, leaving a pulp of glass fibers and resin. They then added those remnants to warmed asphalt, to see if the pulp would act as a binder. Binders such as ground tire rubber and charcoal are typically added to improve asphalt’s stiffness at high temperatures (to reduce rutting) and its pliability at low temperatures (to prevent cracking). The pulp improved both properties, especially when the powder grains were made as small as possible. Zhenming’s team is testing the modified asphalt to check how it holds up to outdoor conditions over time. It is also experimenting with forming the pulp into sheets that could be made into structures such as park benches and fences.
Note: This article was originally printed with the title, "Old Circuit Boards Hit the Road."