Last week, Washington State University news highlighted a new research project that could solve a high-tech waste problem while addressing the environmental challenge of stormwater run-off. WSU researchers have demonstrated the ability to strengthen permeable pavements by adding recycled carbon fiber composite materials.
As WSU explained, unlike impermeable pavement that is used for most roads and parking lots, pervious concrete allows rainwater to freely drain and seep into the ground. Because of increasing concerns about flooding in urban areas and requirements for controlling stormwater run-off, several cities have tried using the pervious concrete in parking lots and low-traffic streets. But because it is highly porous, it is not as durable as the traditional concrete that is used on major roads.
According to WSU, the recycling method, described in the March 2018 issue of the Journal of Materials in Civil Engineering, doesn’t require using much energy. Led by Karl Englund and Somayeh Nassiri, the researchers added carbon fiber composite scrap from Boeing to their concrete mix. They used mechanical milling to refine the composite pieces to create ideal sizes and shapes. The additional material greatly increased both the durability and strength of pervious concrete.
The researchers used cost-effective milling techniques instead of heat to create a reinforcing element from the recycled CFRP. They maintained and made use of the original strength of the composites by keeping them in their cured composite form instead of trying to separate the fibers from the resin. The composite materials were dispersed throughout the pavement mix to provide uniform strength.
“You’re already taking waste — you can’t add a bunch of money to garbage and get a product,” said Englund. “The key is to minimize the energy and to keep costs down.”
While they have shown the material works at the laboratory scale, the researchers are beginning to conduct real-world tests on pavement applications. They are also working with industry to begin developing a supply chain.
“In the lab this works to increase permeable pavement’s durability and strength,” said Nassiri. “The next step is to find out how to make it mainstream and widespread.”