We’ve seen some unusual pavement experiments in our time, with roads being infused with everything from cigarette butts to plastic bags. But when it comes to reinventing asphalt, the Netherlands is leaving nothing to waste. The country has undertaken a two-year pilot project to transform used toilet paper into a blacktop-strengthening agent. And it’s already paved a 1-kilometer stretch of bike path, a section of highway, and a parking lot with the TP-mixed asphalt.
Why, you ask? Well, asphalt is a mixture of stones, sand, and bitumen, which holds everything together. But it’s made stronger when the mixture is combined with a dose of cellulose (plant fibers), which helps the asphalt stick to stones before it fully hardens. Cellulose has the added benefit of wicking water off of roadways when it rains, making them less slippery.
Recycled toilet paper is an abundant source of cellulose. The Dutch flush away roughly 180,000 tons of toilet paper each year. Wastewater treatment plants filter out the toilet paper and typically dry it, and burn it. But the geniuses behind the pilot program—KNN Cellulose and CirTec—decided to use a fancy filer system to clean, sterilize, bleach, and dry the toilet paper before using this high-quality fiber to supply the cellulose in asphalt.
“If you look at it, you would not expect it to have originated from wastewater,” said Chris Reijken, wastewater treatment advisor who’s part of the group overseeing the project. “You can touch it, you can use it, it’s no problem.”