In a major breakthrough for sustainable construction, researchers at RMIT University have teamed up with Bristile Roofing to transform two of Australia’s toughest waste challenges coal ash and recycled glass into durable, low-carbon roof tiles.
The large-scale manufacturing trial, conducted at Bristile’s Melbourne facility, successfully produced hundreds of concrete tiles incorporating 10% harvested pond ash and 10% unwashed glass waste. The result: a lighter, more fire-resistant product that meets all Australian Standards for strength and durability while reducing its carbon footprint by 13%.
“This isn’t just a proof of concept, it’s a ready-to-scale solution,” said project lead Dr Chamila Gunasekara from RMIT. “By replacing 20% of virgin materials with industrial waste, we’re reducing landfill and producing a better-performing product for Australia’s climate.”
A Circular Solution for a Linear Problem
Australia produces around 12 million tonnes of coal ash every year, much of it stored in vast ponds that present long-term environmental risks. At the same time, over 1.3 million tonnes of glass waste are generated annually with more than half still ending up in landfill.
The research team’s life-cycle analysis showed that even modest substitution rates can have a meaningful impact. Using pond ash, which avoids energy-intensive processing, and unwashed glass sand eliminated multiple steps in the traditional cement and aggregate supply chain.
“Every tonne of cement or sand we replace reduces CO₂ emissions, energy use, and extraction pressure,” Dr Gunasekara said. “It’s a tangible step toward a circular economy in construction.”
Engineering Benefits Beyond Sustainability
While the environmental advantages are clear, the engineering performance of the new tiles impressed the team even more.
RMIT Principal Research Fellow Dr Yulin Patrisia explained that pond ash, despite being less reactive than freshly produced fly ash, contributes to better long-term performance.
“Our tests showed improved dimensional stability, less shrinkage cracking, and sustained strength gains over time,” Patrisia said. “That makes these tiles ideal for non-structural yet high-exposure applications like roofing.”
Fire testing also revealed significant improvements in resistance, a critical feature for homes in bushfire-prone areas.
Beyond Roofs: Bricks That Retain Heat and Reduce Carbon
The same concrete mix design is now being applied to structural bricks, integrating 15% pond ash and 20% glass waste. Early results indicate that these bricks not only meet Australian load-bearing and fire standards but also deliver 30% better thermal insulation than conventional cement bricks.
A full life-cycle assessment of the brick variant revealed an 18% reduction in CO₂ emissions, proving that recycled materials can deliver both environmental and performance benefits.
Manufacturing trials are already being planned with commercial partners, setting the stage for large-scale rollout.
From Research to Real-World Results
RMIT’s collaboration with Bristile Roofing is backed by the ARC Industrial Transformation Research Hub (TREMS), a national initiative focused on turning reclaimed waste into engineered materials for circular manufacturing.
Led by Professor Sujeeva Setunge, TREMS brings together researchers from nine Australian universities and 36 partners across government and industry, including Sustainability Victoria, which supported the tile project through its Circular Economy Markets Fund.
Dr Gunasekara said the next phase is about local scalability ensuring a steady supply of waste materials that are consistent in quality and volume.
“This is more than a lab success,” he said. “The industry is ready to adopt. Our next step is to identify reliable regional waste streams and replicate these trials with councils and builders.”
Why It Matters for Builders
For Australian builders, innovations like this point to a future where sustainability and performance go hand in hand. With new standards and consumer expectations driving demand for greener homes, using waste-derived materials could soon be both a commercial and compliance advantage.
Lightweight, fire-resistant, and environmentally responsible, these roof tiles and bricks represent more than a product innovation, they reflect a mindset shift toward designing waste out of construction entirely.
The Good Builder’s Take
As the construction sector grapples with emissions, waste, and cost pressures, projects like this are paving a new path, one where builders, manufacturers, and researchers work together to make sustainability practical.
From factory floors to rooftops, the shift toward low-carbon materials isn’t just coming, it’s already here.
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