A new concrete mix using waste clay, which holds the potential to help decarbonise the construction industry, has been used on the Mickleham Road Upgrade in Victoria.
Decarbonisation is the process of reducing or eliminating carbon dioxide (CO2) emissions.
The new mix uses specially treated waste clay as a replacement for some of the cement binder in concrete, leading to a reduction in CO2 emissions.
Major Road Projects Victoria (MRPV), University of Melbourne and companies Arup and Hanson Australia developed the mix in a joint project that successfully replaced concrete’s cement binder with up to 30 per cent calcined clay.
Concrete traditionally comprises cement, sand, gravel and water. However, it is a major contributor to global carbon emissions, responsible for about eight per cent of total emissions worldwide.
Cement production requires significant energy, and the chemical processes involved in manufacturing releases large amounts of CO2, making it one of the most carbon-intensive materials used in construction.
To address this, MRPV and its partners, including the Department of Transport and Planning, explored the incorporation of calcined clays in concrete as an alternative to traditional cement.
Calcined clays are produced by heating certain types of clay to high temperatures, altering their chemical structure.
Improvements to the calcined clay manufacturing process, as well as further enhancements of the concrete mix design, could see this carbon footprint drop even further.
Extensive testing of the concrete mix was completed to ensure it met industry standards related to compressive strength, workability and durability for large-scale infrastructure projects.
The project team poured the first five cubic metres of the mix in a maintenance strip of the Mickleham Road Upgrade in October, marking an Australian-first for transport infrastructure projects.
The production of calcined clay for the project resulted in about 50 per cent fewer CO2 emissions than cement. Up to 100 cubic metres of the mix is intended for use on Stage 1 of the upgrade.
For more information, bigbuild.vic.gov.au/
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