In a groundbreaking development, scientists at RMIT University have successfully transformed hazardous coal fly ash into a highly sought-after building material that could address a major problem in the construction industry. This breakthrough has the potential to open up a vast untapped resource for cement replacement, offering significant environmental benefits.

The engineers at RMIT replaced an impressive 80% of cement in concrete with coal fly ash, a toxic waste generated by burning dirty fuel in coal-fired plants. This achievement far surpasses the usual limit of 40% in low-carbon concretes. By adding nano additives to modify the concrete's chemistry, the team ensured that engineering performance was not compromised.

This innovation is particularly significant as various governments worldwide are striving to close coal plants, which emit pollutants linked to severe health issues and premature deaths. However, the ash already produced by these plants will remain abundant for decades, even as the world transitions to cleaner energy sources.

Furthermore, the production of cement is responsible for approximately 8% of global carbon pollution, contributing to a warming planet and increasing the frequency and intensity of destructive weather events. Although alternative materials like hempcrete have gained attention, the demand for cement continues to rise.

Scientists have been actively researching ways to reduce harmful pollution in the construction sector, and coal ash has emerged as a promising solution. Another project at the University of Victoria has also explored the use of fly ash and bottom ash to create carbon-sequestering concrete.

RMIT University's research, conducted in collaboration with the Ash Development Association of Australia and AGL's Loy Yang Power Station, also examined pond ash. The team found that their fly ash and pond ash methods met quality and environmental standards, with large concrete beam prototypes demonstrating their effectiveness.

Dr. Chamila Gunasekara, the project lead at RMIT, expressed excitement over the potential of utilizing lower-grade pond ash as a widely available resource for cement replacement. With hundreds of megatonnes of this hazardous waste found in Australia's dams alone, repurposing the ash in construction materials would be a significant victory.

To address concerns about the long-term reliability of less polluting materials in construction, RMIT collaborated with Hokkaido University to develop a computer modeling program. This physics-based model predicts the performance of low-carbon concrete over time, offering insights that can optimize mixes and build confidence in their potential.

The team's findings, published in the journal Cement and Concrete Research, mark an important milestone in the pursuit of low-carbon concretes and could revolutionize construction practices, mitigating the environmental impact of the industry. With the ability to transform hazardous ash into a highly functional building material, scientists are poised to make a major contribution to sustainable construction and a greener future.