From grey concrete to green

Engineering researchers at RMIT University have developed new modelling that shows double the amount of coal ash can be used in concrete as well as overlooked pond ash.

Typical low carbon concretes have no more than 40% of their cement replaced with fly ash yet the  team can recycle twice as much coal ash and halve the amount of cement required and produce a concrete that performs exceptionally well over time.

Coal ash accounts for a fifth of all waste in Australia, with mor than 1.2 billion tonnes produced in 2022 so RMIT has 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.

Project lead Dr Chamila Gunasekara revealed the addition of nano additives to modify the chemistry of concrete allows more fly ash to be added without compromising performance.

Lab studies have also shown that harvesting and repurposing of lower grade and underutilised pond ash from coal slurry ponds at power plants is possible with minimum reprocessing.

Prototypes of large concrete beams have been created using fly ash and pond ash which meet Australian Standards for engineering and environment requirements.

There are hundreds of megatonnes of ash wastes sitting in dams around Australia, and much more globally,” Dr Gunasekara said. “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.”

For more information on this subject visit RMIT NEWS.

Image: Eraring Power Station and ash dam. Source: Ash Development Association of Australia via RMIT.

About the author

Desi Corbett

Desi is the Editor of Concrete in Australia and at the helm of our magazine for 8 years. She was behind the Institute's weekly news bulletins from 2016-2021 and is now writing our focused news items. Desi has been an engineering news and features journalist/editor across all disciplines since 2013 - part of a 30-year career writing for a wide range of industries.