According to a report published on July 23 by the website of Popular Science, engineers have recently developed a method to extract useful materials from cigarette butts. Their findings were published in the Journal of Construction and Building Materials. The study reveals that cigarette filters can significantly improve the strength of recycled asphalt.
Although small in size, cigarette butts accumulate into a staggering volume worldwide. The World Health Organization estimates that smokers discard approximately 4.5 trillion cigarette filters each year. Recent projections suggest this number could rise to 9 trillion by the end of 2025. These waste products degrade extremely slowly, posing serious environmental challenges not only in densely populated areas but also in forests, waterways, and oceans.
In recent years, engineers have begun incorporating additives such as cellulose fibers—similar to those found in cigarette filters—into recycled asphalt mixtures (RAP). This process enhances the strength and binding properties of the asphalt, allowing it to be reused in paving. Recognizing the untapped potential of cigarette waste, researchers from the University of Granada in Spain and the University of Bologna in Italy collaborated to explore new ways to derive practical value from discarded cigarette butts.
The researchers first removed any residual organic matter from the cigarette butts. The remaining filters—typically composed of polylactic acid plastic and cellulose fibers—were then shredded and mixed with a binding wax. Through compression, heating, and cooling processes, this new material was formed into two types of pellets: Type 1 contained only cigarette filter material, while Type 2 included an additional recycling agent.
During manufacturing, when these pellets come into contact with hot, viscous asphalt—a petroleum-based substance—the wax begins to melt. As it dissolves, the plastic and cellulose fibers from the recycled filters integrate into the asphalt mixture, enhancing its flexibility and crack resistance, thereby increasing overall strength.
Researchers at the University of Granada’s Engineering Laboratory evaluated three types of asphalt mixtures containing 40% RAP and varying proportions of the pellets. A control sample containing no RAP was used for comparison.
The team found that every asphalt mixture incorporating cigarette filters demonstrated greater toughness than conventional asphalt. Additionally, the wax made it easier to adjust the viscosity of the asphalt, which reduced the required manufacturing temperature—leading to lower energy consumption and fewer pollutant emissions.
The researchers also suggested that future studies could focus on further optimizing the production process of fiber pellets or increasing the amount of recycling agents to enhance asphalt flexibility. They believe that combining other recycled materials with cigarette filters could further improve the performance of asphalt mixtures while promoting greater sustainability in related industries.