Skip to content
Building Construction

Green concrete recycling twice the coal ash is built to last

RMIT University 3 mins read
Dr Chamila Gunasekara holds a sample of the low-carbon concrete. Credit: Michael Quin, RMIT.

New modelling reveals that low-carbon concrete developed at RMIT University can recycle double the amount of coal ash compared to current standards, halve the amount of cement required and perform exceptionally well over time.

 

More than 1.2 billion tonnes of coal ash were produced by coal-fired power plants in 2022. In Australia, it accounts for nearly a fifth of all waste and will remain abundant for decades to come, even as we shift to renewables.

 

Meanwhile, cement production makes up 8% of global carbon emissions and demand for concrete – which uses cement as a key ingredient – is growing rapidly.

 

Addressing both challenges head-on, engineers at RMIT have partnered with AGL's Loy Yang Power Station and the Ash Development Association of Australia to substitute 80% of the cement in concrete with coal fly ash.

 

RMIT project lead Dr Chamila Gunasekara said this represents a significant advance as existing low-carbon concretes typically have no more than 40% of their cement replaced with fly ash.

 

"Our addition of nano additives to modify the concrete’s chemistry allows more fly ash to be added without compromising engineering performance,” said Gunasekara, from RMIT’s School of Engineering.

 

Finding new opportunities in overlooked pond ash

 

Comprehensive lab studies have shown the team’s approach is also capable of harvesting and repurposing lower grade and underutilised ‘pond ash’– taken from coal slurry storage ponds at power plants – with minimal pre-processing.

 

Large concrete beam prototypes have been created using both fly ash and pond ash and shown to meet Australian Standards for engineering performance and environmental requirements.

 

“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.”

 

New modelling technology 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 explained.

 

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 instil 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.

Relevant studies

Unified hydration model for multi-blend fly ash cementitious systems of wide-range replacement rates’ is published in Cement and Concrete Research (DOI: 10.1016/j.cemconres.2024.107487)   

Sulphate and acid resistance of HVFA concrete incorporating nano silica’ is published in Construction and Building Materials (DOI: 10.1016/j.conbuildmat.2023.132004) 

Long term mechanical performance of nano-engineered high volume fly ash concrete’ is published in Journal of Building Engineering (DOI: 10.1016/j.jobe.2021.103168) 


Contact details:

Michael Quin

michael.quin@rmit.edu.au

+61 499 515 417

Media

More from this category

  • Building Construction, Engineering
  • 23/05/2024
  • 09:00
RMIT University

RMIT and council trial world-first coffee concrete footpath

Freshly brewed coffee concrete may be coming to a street near you after RMIT University teamed up with Macedon Ranges Shire Council to conduct…

  • Contains:
  • Building Construction
  • 21/05/2024
  • 09:38
Australian Constructors Association

FF24 calls industry to shape the vision for construction

Foundations and Frontiers (FF24) is set to become the annual benchmark event, similar to the COP sustainability and Davos economic summits, where goals are set and progress tracked for Australia’s construction industry. With 100 of the industry’s most senior leaders attending invitation-only roundtables and a further 800+ attendees engaging in interactive discussions in the main arena, FF24 will mark the start of a new industry movement. In preparation for FF24 this August, the Australian Constructors Association has released the first discussion paper titled ‘Defining good… and how to achieve it’. Australian Constructors Association CEO Jon Davies said, “This first paper…

  • Contains:
  • Building Construction, Business Company News
  • 20/05/2024
  • 05:00
TSA Riley

??TSA Riley a new global brand for TSA Management and Henry Riley?

EMBARGOED TO 20 MAY 2024 Today, TSA Management marks a significant milestone in its global growth journey by announcing a new name: TSA Riley. The new name represents the organisation’s global reach and 1,000 expert project consultants who helpclients and communities realise the transformative power of their built assets. TSA Riley aspires to lead the industry as a global independent project consultancy. Throughout the infrastructure and property sectors, TSA Riley help clients plan, procure, deliver, optimise, and decarbonise their projects. TSA Riley clients can have a truly end-to-end view of their projects to help them realise the full value and…

Media Outreach made fast, easy, simple.

Feature your press release on Medianet's News Hub every time you distribute with Medianet. Pay per release or save with a subscription.