Concrete teams working for contractors Morgan Sindall, Vinci and Bachy Soletanche spent 29 days with the help of Cemex UK continuously pouring concrete into the slipform shutter of the shaft.

Three cranes delivered concrete to three skips to pour into the 80m deep shaft demanding a total of 11,000m3 of concrete to the scheme.

The concrete was batched on-site and placed at a rate of 100 -150mm  per hour.

The team used a bespoke C50/60 concrete including several admixture blends to control setting times including Isoflex superplasticiser, MR 800D retarder.

The concrete also contained 500 tonnes of steel fibres as reinforcement.

Chris Leese, vice president, Readymix and Mortars, said: “This was a tremendous achievement with nine concrete mixes of different levels of retardation supplied on a regular and continuous basis to form an integral part of this vital structure.

“The materials have been developed using the latest technology and challenge our expertise, to ensure that we can meet the structural requirements of the tunnel.”

The Lee Tunnel is first of two tunnels which will capture an average of 39 million tonnes of London’s sewage and by itself prevent more than 16 million tonnes of sewage mixed with rainwater overflowing into the River Lee each year