RMIT University and Australian roof tile manufacturer Bristile Roofing have developed a sustainable roof tile incorporating coal ash and recycled glass.
Achieving a 13 per cent reduction in carbon dioxide emissions compared to traditional concrete tiles, the innovation addresses the issue of industrial waste management by re-purposing materials that would otherwise contribute to landfill, while offering consumers a durable, fire-resistant roofing option that meets Australian Standards.
Hundreds of the tiles were produced during a full-scale manufacturing trial at Bristile Roofing’s Melbourne facility.
Chamila Gunasekara, Project Lead at RMIT, said the environmental benefit largely stems from using harvested pond ash and unwashed recycled glass sand, which avoids energy-intensive processing and effectively replaces virgin materials.
“By replacing 10 per cent of cement with harvested pond ash and 10 per cent of river sand with unwashed glass waste, a total of 20 per cent virgin material replacement, we not only reduce waste going to landfill but also produce an improved concrete product with enhanced fire resistance, a valuable feature for roofing in Australia’s climate,” said Gunasekara.
In Australia alone, about 12 million tonnes of coal ash are produced annually from electricity generation, with more than 400 million tonnes of coal ash stored in large settling ponds.
Similarly, more than 1.3 million tonnes of glass waste are generated each year, with more than half ending up in landfills.
Yulin Patrisia, Principal Research Fellow at RMIT, said the trial proved researchers can integrate significant volumes of this industrial waste without compromising quality and safety.
“While harvested waste pond ash is less reactive, primarily due to prolonged storage in settling ponds, it remains an attractive material due to its abundance and contribution to long-term engineering performance,” Patrisia said.
“Despite its lower early reactivity, it helps enhance concrete performance over time. Our tests showed better dimensional stability, reduced shrinkage cracking, and continued strength gain, making it ideal for durable, non-structural applications.”
Additional collaborations with local councils and commercial partners are now underway to trial the roof tiles in real-world settings.
“This is more than just a lab success,” said Gunasekara. “We are ready to scale this for industry.”
For more information, visit: www.rmit.edu.au/
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