The Mickleham Road Upgrade – Stage 1 has pioneered the use of an exciting new concrete mix with potential to help decarbonise the construction industry.
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.
The project team poured the first 5m3 of the mix in a maintenance strip in October, marking an Australian-first for transport infrastructure projects.
Up to 100m3 of the mix is intended for use on Stage 1 of the upgrade, which is delivering safer and more-reliable travel on Mickleham Road in Greenvale.
Major Road Projects Victoria, 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.
A core material in construction, concrete traditionally comprises cement, sand, gravel and water. However, cement is a major contributor to global carbon emissions, responsible for around 8% of total CO2 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 so they can partially replace cement in concrete.
Importantly, the production of calcined clay for the Mickleham Road Upgrade – Stage 1 resulted in approximately 50 per cent fewer CO2 emissions than cement, offering a more-sustainable option for the construction industry.
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.
The use of calcined clay as a cement alternative supports the Victorian Infrastructure Delivery Authority’s Transport Infrastructure Decarbonisation Strategy, which aligns with the Victoria’s Climate Change Act and the State Government’s net-zero 2045 ambitions.
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 clays used in the mix were heated to 650°C in a full-scale rotary kiln.
The Mickleham Road Upgrade – Stage 1 is adding lanes in each direction between Somerton Road and Dellamore Boulevard.
As part of Stage 1, the roundabout at Somerton and Mickleham roads will be replaced with a new traffic light intersection, including priority bus lanes, to better-manage traffic flow. Intersection upgrades at Lemonwood Drive, Greenvale Gardens Boulevard and Dellamore Boulevard are now complete, with further upgrades to take place at Hillview Road and Blossom Drive.
The upgrade is also building sections of new shared path for walkers and cyclists.
Once complete, Stage 1 will help to improve safety and ease congestion for the 25,000 drivers using Mickleham Road daily in Melbourne’s north.