TwentyTwo Bishopsgate
Lightweight concrete has been pumped by HeidelbergCements British subsidiary Hanson to a record breaking height in London for the 62-storey tower TwentyTwo Bishopsgate. At 278 metres, the £591million skyscraper, named after its address in Bishopsgate, will be the tallest building in the City of London.
TwentyTwo will offer 62 floors of flexible workspace for up to 12,000 people. The steel-framed tower has a central, supporting jump-form concrete core and perimeter concrete columns.
Hanson is half way through its three-year contract to supply concrete to the project – formerly known as The Pinnacle – and has delivered over 52,000 cubic metres of structural concrete mixes for use in the core, columns, and floor slabs.
All of the mixes contain Hanson’s Regen GGBS (ground granulated blast furnace slag) cement replacement product, which enhances the durability of the concrete while adding to its sustainability credentials. Its use in the raft slab – which contains 68 per cent Regen – also helped minimise the production of heat, reducing the risk of thermal cracking.
Hanson is supplying a range of bespoke mixes to contractor Careys Civil Engineering from its Kings Cross, Silvertown, and Victoria Deepwater plants. These include jump-form and lightweight concrete mixes as well as a complex design for 22 feature columns ranging in size from 4.5 metres to 16 metres high.
"We have pumped the lightweight concrete mixes higher than ever before," said Ian Goddard, technical production manager at Hanson Concrete. "By supplying 56 floors for the project, so far, Hanson has already exceeded the previous record in London which was 50 floors at One Canada Square, Canary Wharf."
Matt Kirsop, project manager at Careys Civil Engineering, added: "Hanson has supplied concrete mixes that have been successfully pumped up to a height of 270 metres. The mixes are highly workable allowing our operatives to efficiently place and achieve the required finish.”
