Tarmac trials new low carbon concrete solution with Align

Tarmac has trialled a new innovative low carbon concrete solution with Align, the joint venture delivering the Central 1 (C1) section of HS2 Phase One

The new low carbon concrete has a carbon footprint following industry BSI PAS2050 calculation rules which equates to a 62% reduction in CO₂e per cubic metre compared to standard CEM I concrete.

With all aspects of concrete production, supply and no carbon off-setting applied, the material delivers a footprint of 133kg/m³ CO₂e, saving 220 tonnes of CO₂e for every 1,000 m³ produced.

Align provided applications at full scale using one of the three Tarmac concrete batch plants at its Chalfont Lane construction site in Hertfordshire. A structural slab forming part of the new viaduct pre-cast factory and a vertical wall were poured.

The mixes exceeded expectations in both fresh and hardened properties and will significantly reduce carbon emissions whilst producing a quality finish and allowing normal construction and demoulding times.

Central 1 section of HS2 Phase One

Tarmac and Align will expand the trial on other available areas of the C1 project and on development of low carbon concrete solutions.

Tarmac is currently providing concrete for the construction of Central 1 section of HS2 Phase One that is being delivered by Align. This includes a 21.6km section of high-speed rail infrastructure incorporating a 3.37km viaduct across the Colne Valley, a 16.04km twin-bored tunnel, and five vent shafts handling both intervention and tunnel ventilation facilities.

Robert Gossling, head of commercial engineering solutions at Tarmac, said: “Against the backdrop of the climate emergency, this project underlines the clear benefits which can be unlocked when clients and contractors collaborate, in this case engaging to help understand and accelerate the adoption of this new low carbon concrete solution.

“Together we’ve shown the material is fit for purpose in slabs and walls, with good repeatability and works with standard production and construction methods.

“This product is a great step along the UK concrete and cement industry’s net zero routemap, and the demonstration will help accelerate adoption of this new concrete.”

Daniel Altier, project director for Align, said: “It is a strategic imperative for Align, reflecting the priorities of our JV partners and in line with HS2 commitments to reduce carbon emissions by 50% and look for opportunities to improve our carbon footprint.

“The early results of this trial are very encouraging and highlight the benefits to be gained through close collaboration with our supply chain partners.”