John F Hunt, working for HS2’s station construction partner, Mace Dragados Joint Venture (MDjv), completed the 232m3 concrete pour – the UK’s largest pour of Earth Friendly Concrete (EFC) – in early September.
The EFC, supplied by Capital Concrete, has been used as a foundation slab that will support polymer silos used for future piling works at the north of the Euston station site. While the foundation is temporary, it will be in use for two years, and historically would have been constructed with a more traditional cement-based concrete.
The use of the product helps support HS2’s aim of net-zero construction by 2035, and achieve its goal of halving the amount of carbon in the construction of Britain’s new high-speed rail line.
HS2 Ltd carbon manager Mark Fenton said the project was on its way to achieving a 50% reduction in carbon emissions compared to traditional construction methods.
“Whilst there have been a lot of examples of using low carbon concrete across the project, the scale of its use at Euston station is a huge step forward in us understanding how it can be used more widely in construction, reducing environmental impact for generations to come,” he said.
EFC is made from a combination of ground granulated blast furnace slag, pulverised fly ash and a high-alkaline chemical, rather than Portland cement. Its geopolymer binder system reduces embodied carbon by around 70%, saving 250kg of CO2 per cubic metre poured.
MDjv programme director Ben Wheeldon said the use of EFC was part of the aim to reduce carbon emissions wherever possible.
“This project is a hotbed for innovation, not just in the decarbonisation space, but generally, and we’re making sure of that by bringing on board the right supply chain partners and encouraging them to be bold with their solutions,” he said.
John F Hunt senior project manager Martin Needham said EFC not only had lower embodied carbon but also higher tensile strength, enabling thinner slab designs, which reduced the overall volume of both concrete and reinforcement.
The site also cut 30 tonnes of CO2 by using 20-yard skips instead of the standard concrete thrust blocks for the temporary works design during removal of a retaining wall. John F Hunt also used GreenD+ Hydrogenated Vegetable Oil (HVO) for all site vehicles instead of diesel, saving around 29 tonnes of CO2.
Also on the Euston site, the HS2 and MDjv team have used LPG generators as a direct replacement for diesel generators, and a new piling method that will provide heating for buildings above.
