Adding a small amount of discarded cigarette butts to bricks during manufacture reduces the energy required to fire them and increases their insulation properties
A research paper from RMIT University, Australia, has revealed the potential for use of recycled cigarette butts (CBs) in brickmaking.
Headed by Dr. Abbas Mohajerani, an Associate Professor at the university’s School of Engineering, the research found that using cigarette butts in bricks introduced three main benefits: it decreased the energy required to manufacture bricks by 9.3% when 1% CB content was included, it increased the brick’s insulation properties, and would offset yearly cigarette production if just 2.5% of bricks produced globally used 1% CB content.
The research was initially conducted to investigate ways of preventing hazardous substances contained within discarded cigarette butts from seeping into the environment. Researchers found that mixing them into bricks trapped the toxic substances in the stubs.
“The proposal was to incorporate 1% CB content by weight in 2.5% of the world brick production to solve a global waste catastrophe,” the paper said.
The researchers found that there was a limit to the amount of cigarette butts that could be used without compromising the strength of the bricks. At 10% CB content for instance, the compressive strength of the bricks dropped by 88% compared to their control bricks.
The paper said it was unlikely that bricks would contain 10% CB content, but the findings demonstrated that even at 1% CB content there was a drop in the loadbearing capacity that could limit the projects these bricks could be used in. The bricks were designed “to satisfy the relevant masonry standards for low-medium rise structural bricks,” the paper wrote.
Additionally, new hardware and safety precautions would need to be adopted to produce the bricks, and to protect those handling production from the harmful substances and pathogens given off by used cigarette butts. The paper advocates that countries build their own CB brick factories, which would also introduce an initial cost that may prove prohibitive.
|Compressive Strength of manufactured brick samples|
|Cigarette butt content (%)||Moisture Content of Brick (%)||Compressive Strength (MPa)|
|0% (Control sample)||15%||43.2|
The bricks’ properties potentially make it attractive for green building projects. With their lower firing point, the paper estimates that if just 2.5% of traditional brick production switched to using 1% CBs, energy savings would reach approximately 20 billion megajoules annually (equivalent to the annual energy use of 1 million homes in Australia).
The bricks’ lower thermal conductivity will also have a “significant influence” on energy consumption in projects they are used in, the paper said, as it “reduces the need to use air-conditioning systems to adjust the temperature”.
You can find the research paper by Dr. Mohajerani et al here.