City of Sydney trials industrial waste concrete

The City of Sydney is testing concrete made using industrial waste from coal-fired power stations and steel manufacturing on a busy inner city road.

A 30-metre section of Wyndham Street in Alexandria has been constructed using the ‘green concrete’.

The council laid 15 metres of traditional concrete and geopolymer concrete, which is a sustainable blend of concrete and recycled materials, to test its durability. 

Made from fly ash and blast furnace slag, it’s estimated geopolymer concrete generates just 300 kilograms of CO2 per tonne of cement, compared to the 900 kilograms from traditional cement production.

Lord Mayor Clover Moore said the city was committed to finding new ways to lower carbon emissions.

“I’m proud that the City of Sydney was Australia’s first carbon-neutral local government and that we’re continuing to take significant steps to reduce our carbon footprint,” the Lord Mayor said.

Wyndham Street is a major road leading to Sydney Airport with a high volume of traffic. Nine sensors have been placed under the concrete to monitor and compare how the ‘green concrete’ performs.

The results from the trial will then be used by University of New South Wales (UNSW) Sydney researchers and the Cooperative Research Center for Low Carbon Living (CRCLCL) to create industry guidelines for geopolymer concrete.

Mr. Moore said 70 per cent of concrete produced goes into pavements and footpaths leaving great potential to further reduce emissions while providing quality infrastructure.

The low CO2 concrete has the potential to put 400 million cubic tonnes of waste from the coal and steel industries to good use.

The UNSW Sydney researchers will monitor the road’s performance for up to five years.

Professor Stephen Foster, Head of School of Civil and Environmental Engineering, is the CRCLCL project lead and described the trial as “a huge step forward.”

“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,” Professor Foster said.

“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.”

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