A record-breaking quantity of Earth friendly concrete has been poured for the £1bn London Power Tunnels project.

The seven-year project to rewire South London via deep underground tunnels will need 32.5km of 3m diameter tunnels constructed deep below the road network between Wimbledon and Crayford, which will carry high voltage electricity cables. Along with less disruption, an additional benefit is that new cables can be installed in the tunnels to meet future demand.

With 736,000 litres of more sustainable, cement-free concrete the base of the 55m deep tunnel drive shaft at National Grid’s Hurst Substation in South London has been completed. The cement free solution was developed by Wagners and supplied by Capital Concrete and uses a binder of ground granulated blast furnace slag and fly ash geopolymer concrete system chemically activated by the use of industrial waste products instead of cement. The concrete reduces carbon by around 64 per cent in comparison to concrete which would have traditionally been used.

The record-breaking pour was needed to infill the base of the 55m deep tunnel shaft to its permanent level, following the successful completion of 9.2km of tunnelling over 2 tunnel drives from Hurst to Eltham and Crayford.

Elsewhere on the London Power Tunnels project, there are several measures in place to reduce the environmental impact of construction and keep National Grid on track to achieve net-zero carbon construction by 2025/26.

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