The recycled material came from used printer toner cartridges | LEFT: Wikimedia Commons; RIGHT: ChatGPT
California tested asphalt that contained recycled plastic from discarded printer toner cartridges on State Route 99 in Elk Grove, south of Sacramento in 2022. The project began with a test on a highway shoulder before the modified asphalt was placed across all lanes of a 500-foot section. The highway project conducted an earlier test in a commercial parking lot in 2021, where Granite had used the post-consumer plastic material there before moving to the highway application. The State Route 99 section provided a test under regular traffic, which included heavy trucks and seasonal temperature changes.
Granite Construction later reported that thousands of heavy trucks traveled across the section through hot and cold weather without visible cracking or rutting. The work was part of the Cosumnes Bridge Replacement Project in Sacramento County, and researchers were interested in whether the modified asphalt could maintain its performance under conditions that cause conventional pavement to deform or crack.
The early results were promising, but the Highway 99 project was still a field trial. Granite also calculated potential environmental benefits from using recycled plastic in asphalt, with its report estimating that the modified mixture could reduce the mix’s global warming potential by at least 5% compared with a similar mixture without recycled plastic. Those figures were Granite’s calculations for the larger mixture and should not be treated as a measurement of the 500-foot Highway 99 section alone.
The University of Nevada , Reno said that researchers continued laboratory and field testing to study the material’s long-term resistance to cracking and rutting.