Coffee cups could be reused in composite building materials

Experimental research by Victoria University’s (VU) College of Engineering and Science has found that powder made from recycled takeaway coffee cups and other plastic waste material could be used as a standard ingredient in some composite building materials.

Coffee cups in binCompleting a comprehensive pilot study in 2020 in collaboration with Wyndham City Council, the research team tested a range of new materials developed by replacing the fine aggregate usually used in the composite mix with polyethylene (PE) powder made from used plastic coffee cups.

The experiments investigated whether this new type of composite material satisfies feasibility, environmental and fundamental performance requirements, in accordance with building codes and Australian Standards.

Using the powder to replace up to 10 per cent of the fine aggregate normally used in the composite mix, the researchers measured the compressive strength, and the thermal and fire-hazard properties of bricks and panels.

Although the tests found there was a drop in compressive strength, the material could still be suitable for low-stress applications such as concrete footpaths and Besser blocks. The researchers found that the use of PE powder boosted the composite material’s insulation properties, meaning it could potentially be beneficial for producing lightweight insulating panels.

The use of plastic waste in new building materials could contribute to achieving Australia’s target of recovering 80 per cent of its waste by 2030, with the project seeking funding for its next phase, which will focus on large-scale testing ahead of commercialising the new eco-products.

Zora Vrcelj, Associate Professor in Structural Engineering at Victoria University, said: “Translating our research findings into commercially viable applications has the potential to reduce the volume of plastic waste going to landfill, while also lessening the building sector’s reliance on extracted natural resources.

“Using locally and excessively available waste materials as a raw component for producing building materials also reduces lifecycle environmental impacts and promotes sustainable local industries.”