Sydney trials world-first concrete road made from industrial waste

New segment of geopolymer road next to classic concrete

Sydney Trials A World First

A new type of concrete is being trialled in Alexandria, Sydney as part of the City of Sydney’s commitment to reduce carbon emissions.

In a world-first green road trial, a 15-metre section on Wyndham Street has been replaced with Geopolymer concrete made using industrial waste from coal-fired power stations and steel manufacturing plants. The City is putting this sustainable blend of concrete and recycled materials to the test on the busy inner-city street with nine sensors positioned under the concrete for monitoring and assessment. The street also features 15 metres of traditional concrete for comparison.

Results from the green road trial will be used by UNSW Sydney researchers and the CRC for Low Carbon Living (CRCLCL) to create the first set of industry guidelines for Geopolymer concrete.

Lord Mayor Clover Moore said that the City of Sydney was Australia’s first carbon-neutral local government and they were committed to efforts to reduce their carbon footprint. The Geopolymer project could make a real difference in slashing carbon emissions, he said. 

“Local governments are responsible for maintaining local roads, so if we can purchase more environmentally sustainable materials, we can fight climate change and provide quality infrastructure for our community. 

“We’re continually working with concrete suppliers to reduce the amount of pollution and greenhouse gases emitted during the production of concrete for our local roads, and we already use sustainable green concrete for all our footway renewal works – which adds up to 25,000m² per year,” Moore added.

Made from industrial wastes such as fly ash and blast furnace slag, Geopolymer generates just 300 kilograms of CO2 per tonne of cement, compared to the 900 kilograms from traditional cement production. Coal and steel industries worldwide generate about 400 million cubic tonnes of waste, most of which is stored on site. The Geopolymer project opens up the potential to put this waste to good use. 

The trial will be monitored for road performance by UNSW Sydney researchers for up to five years. Professor Stephen Foster, head of School of Civil and Environmental Engineering, and the CRCLCL project lead, said that the trial will help drive step change in the industry.

According to Foster, Geopolymer research has been undertaken since the 90s, but it’s only being commercialised now. The data collected by the team in the first three to 12 months of the trial will be used to confirm their models and strengthen predictions.

Dr Tommy Wiedmann, associate professor of sustainability research at UNSW says replacing traditional concrete with Geopolymer concrete would save 12,000 kilotons of CO2 per year.