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    Cigarette butts could soon help cool our cities

    Kirsty Sier

    The cigarette butts that litter our public footpaths are rightly thought of as an environmental waste problem. Not only do they have lethargic rates of biodegradability, but once they do break down, they leach a number of toxic heavy metals – such as arsenic, chromium, nickel and cadmium – into our soil and waterways. Soon, however, cigarette butts could be making amends for their past wrongdoings, and contributing to the sustainability of our cities.

    A Melbourne scientist has found a way to turn cigarette butts into a brick-like building material that is capable of handling heavy traffic and improving heat conductivity. Dr Abbas Mohajerani, a senior lecturer at RMIT’s School of Engineering, found that bricks containing a mixture of asphalt and cigarette butts can save on both production costs and environmental impact.

    “I have been trying for many years to find sustainable and practical methods for solving the problem of cigarette butt pollution,” says Mohajerani in research published to the Construction and Building Materials journal on Monday.

    “In this research, we encapsulated the cigarette butts with bitumen and paraffin wax to lock in the chemicals and prevent any leaching from the asphalt concrete. The encapsulated cigarette butts were mixed with hot asphalt mix for making samples.

    “Encapsulated cigarette butts developed in this research will be a new construction material which can be used in different applications and lightweight composite products.

    “This research shows that you can create a new construction material while ridding the environment of a huge waste problem.”

    According to research, roughly 6 trillion cigarette butts are produced every year, with most of these eventually ending up as environmental waste. These figures are only predicted to increase with a rising population.

    By trapping the toxic chemicals contained in cigarette butts within building materials, Mohajerani’s work could help combat a huge pollution problem. Further, the product’s thermal conductivity could make a positive contribution to the environment by helping to mitigate the urban heat island effect.

    “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,” says Mohajerani.

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