Hanson celebrates TwentyTwo contract milestone
First publishedon www.AggBusiness.com
On completion, TwentyTwo will offer 62 floors of flexible workspace for up to 12,000 people
UK construction materials giant Hanson has reached a key milestone in its contract to supply concrete to TwentyTwo, a £591 million, 278-metre tower which is set to be the tallest building in the City of London on completion next year.
The company is half way through its three-year contract to supply concrete to the project – formerly known as The Pinnacle – and has delivered over 52,000m³ of structural concrete mixes for use in the core, columns and floor slabs.
All of the mixes contain Hanson’s Regen GGBS (ground granulated blastfurnce slag) cement replacement product, which enhances the durability of the concrete while adding to its sustainability credentials. Regen is manufactured from a by-product of the iron making industry and using it to replace one tonne of Portland cement reduces the embodied CO2 of the concrete by around 850kg. 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.
TwentyTwo, located in Bishopsgate, 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 has reached a key milestone in its contract to supply concrete to London's TwentyTwo tower project
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 54 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, 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.”