Holcim Australia have assisted Rail Projects Victoria, in partnership with Laing O’Rourke, to effectively lower carbon emissions through progressive solutions. These solutions relate to the use of fly ash and slag as applicable alternatives to traditional cement mixes.

Since August 2021, the Australian Roads Research Board (ARRB), on behalf of Victoria’s Department of Transport and Planning (DTP), approved a mix with 70% cement replacement with industrial by-products.

This is 30% higher than the 40% limit in the standard and 55% higher than the Level Crossing Removal Project’s business-as-usual rate of 15%.  

This change will prevent almost 4,000 tonnes of carbon dioxide across three separate sites.

The General Manager of Sustainability & Environment at Laing O’Rourke, Hollie Hynes, is driving the change, stating “three of the projects in delivery are using this mix, showcasing how we can create sustainable solutions that have ongoing benefit in the broader industry.”

Hynes also commented on the carbon reduced concrete mix: “It’s more durable with regards to chemical attack and corrosion, and its lower heat of hydration, while reducing early-age strength development, reduces risks from thermal cracking as the concrete sets. This mix could be used for slabs — it can be designed to meet all the key performance requirements — however, we would need to conduct more investigations and possibly implement more controls.”

The team at Laing O’Rourke also stated that there were little to no engineering challenges when dealing with the lower-carbon cement mix. “There are some differences,” Hynes said. “But one of my team members, when I was talking with them about it, said it was quite unremarkable in itself. There’s a programming consideration because it takes longer to cure initially. It’s not horrifically slow, but it does need to be taken into consideration.”

Holcim stated they were “immensely proud to contribute to projects that drive sustainability and innovation in the construction industry. Together with Laing O’Rourke, we’re shaping a more sustainable future for construction.”