Sydney drives world-first green roads trial

The City of Sydney puts environmentally friendly concrete to the test.

In the first trial of its kind, we’ve taken industrial waste from coal-fired power stations and steel manufacturing to create a new roadway.

Working with researchers from the University of NSW, we’ve replaced a section of roadway on Wyndham Street in Alexandria to test the green concrete’s durability.

Made from fly ash and blast furnace slag, geopolymer concrete is a sustainable blend of concrete and recycled materials.

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Geopolymer generates just 300kgs of CO2 per tonne of cement, compared to 900kgs from traditional cement production. The carbon emissions savings is equivalent to the electricity used by an average household every 2 weeks.

With 70% of the concrete produced today going into pavements and footpaths, using products like geopolymer concrete for our roads and footpaths has great potential to further lower emissions from our operations.

As a major road leading to Sydney Airport, Wyndham Street’s high traffic volume provides the perfect conditions for the trial.

The new roadway is made from industrial waste

9 sensors have been positioned under the concrete to monitor and compare how the geopolymer concrete performs.

University of NSW researchers and the Cooperative Research Centre for Low Carbon Living will use results from the trial to create the first set of industry guidelines for geopolymer concrete.

Research has been undertaken since the 1990s, but it’s only now this concrete blend is being explored as a product that is not only better for the environment, but also commercially viable.

Sensors were laid to test the performance of the 'green' concrete

The low CO2 concrete has the potential to put the 400 million cubic tonnes of globally documented waste from the coal and steel industries to good use. While a small amount is currently used in construction, much of it is currently stored on site.

University of NSW researchers will monitor the road performance for up to 5 years.

Using products like geopolymer concrete helps us lower emissions from our operations

Professor Stephen Foster, head of school of civil and environmental engineering, is the project lead. He describes the trial as “a huge step forward”.

“This trial will help drive step change in the industry. Many concrete companies are already doing a lot to change, but this trial really gives it another push,” Stephen said.

The concrete blend is being explored as a sustainable and commercially viable product

“While we’ll monitor the road performance for up to 5 years, a lot of the data collected in the first 3 to 12 months of this world-first trial will be used to confirm our models and strengthen our predictions.

Results from the trial will help create the first set of industry guidelines for geopolymer concrete

“Concrete contributes 7% 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," he said.

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