Stanhope

The oval nine-storey headquarters built for Legal & General on a rare island site was a leader in the use of recycled concrete.

The basement and upper floor slabs are made of 100 per cent china clay stent, a by-product of china clay that is usually dumped on spoil heaps.  By using 6000 tonnes of stent at Coleman Street, the equivalent was diverted from landfill and the amount of primary aggregate that had to be quarried was reduced.  Pulverised fuel ash was also used to replace a portion of Portland cement, up to 40 per cent of the structure in some cases, while reinforcement was manufactured using 100 per cent scrap metal.  This approach increased the overall recycled/secondary content of the concrete tenfold, from the five per cent typical of most construction to 50 per cent.

The project also used an innovative twin wall system for core construction, which improved the speed and safety of the development and reduced the formwork.

Despite the constraints of the St Paul's heights code, 180,000 sq ft of space has been produced on the site.

Ground conditions were complex, with a Post Office rail tunnel running diagonally under the site and a large number of fibre-optic services having to be moved.  The entrance to a City of London basement carpark had to be moved further along London Wall to accommodate the development.