16 June 2025
Originally published in Concrete in Australia Magazine 51.2 (June 2025)
This innovative concrete, using the industrial by product furnace bottom ash as supplementary cementitious material and partial sand replacement, marks a significant step toward sustainable construction.
According to SmartCrete CRC Research Director and University of Technology, Sydney (UTS), Professor Vute Sirivivatnanon: “This eco friendly concrete diverts waste from landfill, reduces embodied carbon compared to traditional concrete, and lessens the need for natural sands.”
Traditionally limited to road-base and sub-base applications, furnace bottom ash now finds renewed use through this project, with the aim of broadening its application and enhancing both recycling and construction practices.
The Eco-Friendly Concrete Using Industrial By-Products project is a collaboration with the University of Newcastle (UON), led by Professor Patrick Tang. It brings together industry partners Daracon, Delta Electricity, Ash Development Association of Australia, and Transport for NSW (TfNSW). The team is working to establish treatment procedures to make furnace bottom ash as effective as fly ash, develop concrete products that meet Australian Standards, and implement them in local council projects like footpaths and pavements.
On a sunny day earlier this year, the team poured the new concrete alongside a control mix of GP cement concrete. Each mix featured a compressive strength of25 MPa, a 10-milimetre-maximum-size aggregate and 10-metre cast. The weather was perfect for natural curing-mild, followed by a shower two hours after completion.
The control mix was placed first in the mid-section of the path, with the test mix being placed next in the curved section. Both mixes were easily placed and finished with little slump loss. The test mix exhibited slightly more bleeding, which can be beneficial for concrete placement on hot and windy days. It presented a darker grey hue due to the colour of the furnace bottom ash – potentially a preferred colour for customers.
Professor Sirivivatnanon noted: “The trial pour proceeded seamlessly, from well-organised site preparation through to concrete delivery, placement, sampling and testing.”
Following the pour, samples were cast and cured on-site before being sent to the Civil Lab at the University of Newcastle for stripping, further curing, and testing. The tests will assess the density, compressive and flexural strengths, and drying shrinkage of the hardened samples. Once completed, the team will compile a report summarising their observations, findings, and test results.
“We are looking forward to further developing this new concrete product and its specifications to meet Australian Standards,” Professor Sirivivatnanon said, highlighting the project’s role paving the way for a sustainable future in concrete construction.
