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Discover sustainable concrete that uses 80% coal ash, reducing carbon emissions in construction without compromising durability
RMIT University has developed an innovative low-carbon concrete that can recycle twice as much coal ash as current standards, halve the amount of cement required and maintain exceptional performance over time. This innovation addresses two environmental problems critical in construction: coal ash production and carbon emissions from cement.
In 2022, coal-fired power plants generated more than 1.200 million tons of coal ash. In Australia, this ash represents almost a fifth of all waste and will continue to be abundant for decades, even as renewable energy sources are adopted.
Furthermore, cement production contributes 8% of global carbon emissions, and demand for concrete, which uses cement as a key ingredient, is growing rapidly.
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CONSTRUCTION – FREE MARKET
Innovation in construction
RMIT engineers, in collaboration with AGL's Loy Yang Power Station and the Ash Development Association of Australia, were able to replace 80% of the cement in concrete with coal fly ash.
Dr Chamila Gunasekara, project leader at RMIT, highlighted that this represents a significant advance, as existing low-carbon concretes replace a maximum of 40% of fly ash cement.
Addition of Nano Additives
The key to this advancement is the addition of nano additives to modify the chemistry of the concrete, allowing the incorporation of more fly ash without compromising the structural performance of the construction. This modification also allows the use of previously underutilized lower quality “pond ash” obtained from coal sludge storage tanks at power plants, with minimal processing.
Prototypes and Standards
Large prototype concrete beams were created for construction using both fly ash and pond ash, demonstrating that they meet Australian structural performance standards and environmental requirements. Preliminary results show similar performance with lower grade pond ash, which could open up a hugely underutilized resource for cement replacement.
Long-Term Modeling and Resilience
A pilot computer modeling program, developed in collaboration with Dr. Yogarajah Elakneswaran of Hokkaido University, was used to predict the long-term performance of these new concrete mixes.
According to Dr. Yuguo Yu, an expert in virtual computational mechanics at RMIT, this approach allows us to understand how newly developed materials will resist the passage of time.
Physics-Based Model
The physics-based model created by RMIT reveals how the different ingredients in the new low-carbon concrete interact over time. For example, it can be seen how fast-drying nano additives act as a performance enhancer during the initial drying stages, compensating for the large amounts of fly ash and slower-drying pond ash.
Impact and Future in Construction
This research, supported by the ARC Industrial Transformation Research Center for Transforming Recovered Waste Resources into Materials and Engineering Solutions for a Circular Economy (TREMS), has the potential to revolutionize sustainable construction. Led by RMIT Professor Sujeeva Setunge, TREMS brings together leading scientists, researchers and industry experts to minimize landfill waste and reuse recovered materials in construction and advanced manufacturing.
The adoption of this low-carbon concrete not only represents an innovative solution for coal ash waste management, but also significantly reduces the construction industry's carbon emissions. The collaboration between RMIT, Hokkaido University and industrial partners promises a large-scale implementation of this technology, marking an important step towards more sustainable and environmentally responsible construction.
Source: rmit.edu.au
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