An educational video on the World Health Organization’s calls it “the plastic problem that no one is talking about.” They mean cigarette butts, the most common type of plastic litter globally. Per the WHO, 4.5 trillion cigarette butts are thrown in the environment every year.
Conventional and electronic cigarette butts not only contain plastic, they are loaded with nicotine salts, heavy metals, and lead. When disposed improperly, cigarette waste leaches that toxic waste into the environment. But now researchers have found a use for those cigarette butts.
Instead of litter on roads, they propose using the butts as an additive to asphalt that would strengthen roads. In a new study published in the journal Construction and Building Materials, they say that the additive would improve crack resistance and reduce the need for repairs.
To increase the sustainability of transportation, there has been a push recently to include recycled materials in road construction. Waste plastic, bio-based materials and scrap tire rubber have all been put to use to make roads.
A convenient, plentiful material for recycled roads though is old asphalt that is removed from road surfaces during maintenance or reconstruction. This recycled asphalt can be crushed and mixed with new asphalt or concrete to make the base material for roadways.
But old asphalt does not have the same strength and low-temperature resistance, so it can make roads deteriorate faster. So it has to be mixed with special chemical agents, and for this mixing to be uniform, encapsulating the recycling agents in fiber pellets is key.
So a team from the University of Granada and the University of Bologna found a way to encapsulate the recycled asphalt into fibrous pellets made from waste e-cigarette butts. E-cigarette filters are made mainly of cellulose and polylactic acid fibers. After removing the ashy residue from the ends of used e-cig filters, the team shredded and mixed the clean e-cig butts with a wax binder. Then they pressed, heated, and cut the mixture into the form of pellets.
Finally, the researchers mixed the pellets with old asphalt and added about 40 percent by weight of this mixture to fresh asphalt material. When the pellets come into contact with the hot fresh asphalt, the wax melts and releases the recycled cellulose and plastic fibers from the cigarette butts.
The fibers reinforce and strengthen the asphalt and also make the material more ductile and flexible, making it more resistant to cracking under stress. Tests showed that the encapsulated recycling agent showed six times higher crack-resistance than pellets made only of the e-cig waste fiber. Plus, the wax changes the asphalt’s viscosity, allowing it to be produced at lower temperatures, which consumes less energy.
The researchers write that “future research should focus on optimizing the production processes for recycling agent-encapsulated fibre pellets or increasing the dosage of recycling agent to further enhance their performance characteristics.”
Source: Yunfei Guo et al. Use of engineered pellets containing E-cigarette butts and a recycling agent for stone mastic asphalt mixtures incorporating recycled asphalt. Construction and Building Materials, 2025.
Image: ©Anthropocene Magazine
