O’Rourke carried-out a 24-hour continuous pour delivering 3,200m3 of concrete – its largest concrete pour ever completed in one sitting.

The site team took delivery of 400 trucks of concrete from factories in Kings Cross and Silvertown.

The newly-formed raft slab will carry the weight of the full concrete structure, distributing the weight evenly across 36 large diameter bearing piles.

The pour filled an excavated hole 18m deep, resulting in a raft slab up to 4.5m thick.

This concrete slab will provide stability for the 170m-high tower in the face of wind resistance, creating an internal lever arm across its base and providing a large mass to anchor the form.

It is estimated that the concrete will take 56 days to achieve its specified target strength.

Once completed by main contractor Brookfield Multiplex in spring 2018, the tower will stand at 50 storeys high and contain 57,000 tonnes of concrete structure.

Michael Bryn – Jones, Managing Director, St George South London, said: “We are delighted with the ongoing building progress at One Blackfriars.

“This vast concrete pour marks a significant milestone in the construction of the tower and it is thrilling to see a record-breaking pour conducted at a St George site.

“Work will now commence apace and Londoners will be able to watch as One Blackfriars begins to take shape on the city skyline.”

For the latest developments in the sector find out more about the Evolving Concrete exhibition here