Scientists have discovered a novel use for discarded cigarette butts in building roads, an advance that could reduce heat in urban areas as well as tackle the problem of waste accumulation.
Trillions of cigarette butts are produced every year worldwide, with most discarded into the environment. They take ages to break down while their toxic chemical load is released into creeks, rivers and the ocean.
Researchers from Royal Melbourne Institute of Technology (RMIT University) in Australia have demonstrated that asphalt mixed with cigarette butts can handle heavy traffic and also reduce thermal conductivity.
The team encapsulated cigarette butts with bitumen and paraffin wax to lock in the chemicals and prevent any leaching from the asphalt concrete.
The encapsulated cigarettes butts were then mixed with hot asphalt mix for making samples.
"These encapsulated cigarette butts developed will be a new construction material which can be used in different applications and lightweight composite products," said Abbas Mohajerani, from RMIT University.
"This research shows that you can create a new construction material while ridding the environment of a huge waste problem," Mohajerani added.
This means the product could not only solve a huge waste problem but would also be useful in reducing the urban heat island effect common in cities, researchers said.
An urban heat island (UHI) is an urban area or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities.
About six trillion cigarettes are produced every year, leading to more than 1.2 million tonnes of cigarette butt waste. These figures are expected to increase by more than 50 per cent by 2025, mainly due to an increase in world population.
"Cigarette filters are designed to trap hundreds of toxic chemicals and the only ways to control these chemicals are either by effective encapsulation for the production of new lightweight aggregates or by the incorporation in fired clay bricks," Mohajerani said.
The study was published in the journal Building Materials.