Major Road Projects Victoria has helped develop a low-carbon concrete mix using calcined clays, offering a more-sustainable option in the construction industry
A low-carbon concrete mix using calcined clays has been developed by Major Road Projects Victoria (MRPV), Arup, The University of Melbourne and Hanson Australia.
The joint project successfully replaced concrete’s cement binder with up to 30 per cent calcined clays.
Concrete traditionally is made up of cement, sand, gravel and water, with cement responsible for around eight per cent of total CO2 emissions worldwide, according to MRPV.
This is because the production of cement requires significant energy, and the chemical processes involved in manufacturing releases large amounts of CO2.
To help address this, the incorporation of calcined clays in concrete was explored to replace some of the traditional cement used.
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MRPV says calcine clays are produced by heating certain types of clay between 600 and 900 degrees Celsius, altering their chemical structure to create a reactive material capable of binding together the concrete.
Compared to cement, the production of calcined clay for this project resulted in a carbon emissions reduction of approximately 50 per cent.
Improvements to the calcined clay process could see this carbon factor drop even further and offering a more-sustainable option for the construction industry, MRPV adds.
Testing has shown that the low-carbon concrete mix exceeded the target compressive strength of 32 MPa at 28 days – a key benchmark for structural concrete.
The mix also demonstrated workability and durability, with MRPV confirming its suitability for large-scale infrastructure projects.
MRPV is currently using the new mix on Melbourne’s Mickleham Road Upgrade in Melbourne’s north.