Concrete made using industrial waste from coal-fired power stations and steel manufacturing is being used in a world-first road trial in Sydney.
The City of Sydney is putting the product to the test on a busy inner-city street leading to Sydney Airport, replacing a 30m section of Wyndham St, Alexandria with 15m of Geopolymer concrete, a sustainable blend of concrete, fly ash and blast furnace slag, alongside 15m of traditional concrete. Nine sensors have been positioned to monitor and compare how the two products perform. The high volume of traffic provides the perfect conditions for the trial.
Researchers from the University of NSW and the Cooperative Research Centre for Low Carbon Living (CRCLCL) will monitor the road’s performance for up to five years, using the results to create the first set of industry guidelines for Geopolymer concrete.
Because it incorporates recycled materials, Geopolymer generates just 300kg of CO2 per tonne of cement, compared to the 900kg for traditional cement production, saving the equivalent of the electricity used by an average household every two weeks.
Research has been undertaken since the 1990s, but it’s only now that it is being explored as a product that is not only better for the environment, but also commercially viable.
The low CO2 concrete has the potential to put the 400 million tonnes of waste from the coal and steel industries globally to good use. While a small amount is currently used in construction, much of it is currently stored on site.
Professor Stephen Foster, Head of UNSW’s School of Civil and Environmental Engineering and the CRCLCL’s project lead, describes the trial as “a huge step forward”.
“This trial will help drive step change in the industry,” he says. “Many concrete companies are already doing a lot to change, but this trial really gives it another push.
“While we’ll monitor the road performance for up to five years, a lot of the data collected in the first three to 12 months of this world-first trial will be used to confirm our models and strengthen our predictions.
“Concrete contributes seven per cent of all greenhouse gas emissions and in 2018 the world produced about 4.1 billion tonnes of cement, which contributed about 3.5 billion tonnes of CO2.
“Alternative, low CO2 concrete materials offer potential benefits in reducing the greenhouse gas emissions associated with conventional concrete.
“This trial is important because we need demonstration projects to accurately assess the performance of Geopolymer over time so that there can be broader uptake.”
Industry partner Craig Heidrich, Executive Director of the Australian (Iron and Steel) Association and Ash Development Association, says the benefits of the trial will be far-reaching.
“Our collaboration with organisations such as the City of Sydney and the publication of the research findings will further de-mystify and promote the use of Geopolymer concrete in construction,” he says.
“Geopolymer concrete has great engineering properties. It is a durable, high performance product that has a low carbon footprint when used in construction.
“It's a fundamental tenet in business that you need to be constantly innovating and investing into new technologies. This trial will provide real examples of Geopolymer concrete use that we can all use.”