The HS2 Skanska Costain STRABAG joint venture has secured extra funding to trial repurposed London Clay as a low carbon alternative to cement.

The JV is working with Arup, Tarmac, the University of Leeds and Sika UK along with Expedition Engineering and the Mineral Product Association on the trial funded by Innovate UK to help accelerate the decarbonisation of the concrete industry.

The team is continuing to develop the replacement of carbon intensive Portland Cement with repurposed London Clay from site excavation work.

By calcinating (heating to activate) London Clay excavated from the tunnel activities the team is using it as a replacement for Portland Cement in concrete for the HS2 permanent works.

Apostolos Tsoumelekas, Materials Engineering Manager who has been heavily involved in developing the product said: “This innovation was first sparked by a discussion with an expert in Arup who had been researching the applications of calcined clays in concrete. Working together with our customer and the supply chain we have been able to help turn this idea into reality.

“The clay that is excavated from the HS2 tunnels is essentially a waste product. We have developed a process which calcines the clay and grinds it to a powder transforming it into a useful resource which can then be added to concrete replacing Portland cement.

“The results have been impressive and hopefully if it’s scaled up it could really help speed up the adoption of low-carbon concrete for commercial use.”