Environmental News

‘Exciting’ new research new opportunity for green concrete

RMIT

New research from RMIT University has shown ‘exciting’ results for low-carbon concrete which uses alternative materials like coal ash and pond ash.  

The modelling indicated that low-carbon concrete, from RMIT University, had the potential to recycle double the amount of coal ash and maintain performance levels. Compared to current standards, the amount of coal ash used in this low-carbon cement would halve the amount of cement required.  

RMIT University partnered with AGL’s Loy Yang Power Station and the Ash Development Association of Australia to substitute 80 per cent of the cement in concrete with coal fly ash. 

“Our addition of nano additives to modify the concrete’s chemistry allows more fly ash to be added without compromising engineering performance,” RMIT project lead Dr Chamila Gunasekara said.  

This is considered a significant advancement for the material given most low-carbon concrete substitutes about 40 per cent of cement with fly ash.  

Eraring Power Station and ash dam from above, with Lake Macquarie in the background. Image: Ash Development Association of Australia.

The research has also shown capability to use other alternative materials in the composition. One possible material included pond ash, which is taken from coal slurry storage ponds at power plants.  

“It’s exciting that preliminary results show similar performance with lower-grade pond ash, potentially opening a whole new hugely underutilised resource for cement replacement,” Gunasekara said. 

“Compared to fly ash, pond ash is underexploited in construction due to its different characteristics. There are hundreds of megatonnes of ash wastes sitting in dams around Australia, and much more globally.” 

“These ash ponds risk becoming an environmental hazard, and the ability to repurpose this ash in construction materials at scale would be a massive win.” 

Modelling advance shows low-carbon concrete’s long-term resilience  

A pilot computer modelling program developed by RMIT in partnership with Hokkaido University’ Dr Yogarajah Elakneswaran has now been used to forecast the time-dependent performance of these new concrete mixtures. 

According to Dr Yuguo Yu, an expert in virtual computational mechanics at RMIT, a longstanding challenge in the field has been to understand how newly developed materials will stand the test of time.  

“We’ve now created a physics-based model to predict how the low-carbon concrete will perform over time, which offers us opportunities to reverse engineer and optimise mixes from numerical insights,” Yu said. 

The RMIT team: (l-r) Dr Yuguo Yu, Professor Sujeeva Setunge, Dr Dilan Robert, Dr Chamila Gunasekara, Dr David Law. Image: Michael Quin, RMIT.

This pioneering approach – recently unveiled in the prestigious journal Cement and Concrete Research – reveals how various ingredients in the new low-carbon concrete interact over time.  

“We’re able to see, for example, how the quick-setting nano additives in the mix act as a performance booster during the early stages of setting, compensating for the large amounts of slower-setting fly ash and pond ash in our mixes,” Gunasekara says. 

“The inclusion of ultra-fine nano additives significantly enhances the material by increasing density and compactness.” 

This modelling, with its wide applicability to various materials, marks a crucial stride towards digitally assisted simulation in infrastructure design and construction. 

By leveraging this technology, the team aims to instill confidence among local councils and communities in adopting novel low-carbon concrete for various applications. 

This research was enabled by the ARC Industrial Transformation Research Hub for Transformation of Reclaimed Waste Resources to Engineered Materials and Solutions for a Circular Economy (TREMS). 

Led by RMIT’s Professor Sujeeva Setunge, TREMS brings together top scientists, researchers and industry experts from nine Australian universities and 36 state, industry, and international partners to minimise landfill waste and repurpose reclaimed materials for construction and advanced manufacturing. 

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