Saint-Gobain Weber Takes The Pressure At Heathrow Airport T5 Tunnels

Published by Jackie Biggin for Weber in Central Government

A high specification and robust industrial flooring screed by Saint-Gobain Weber, the leading UK formulator and manufacturer of innovative materials in the external wall insulation, render, tile fixing, construction mortars and commercial floor sectors, has been specified in the construction of below-ground access and service tunnels at Heathrow Airport Terminal 5.

Master planners and transport architects Pascall+Watson, London, worked as lead designers alongside major contractor Carillion to complete the BAA-owned Terminal 5, enabling British Airways to consolidate its entire Heathrow fleet operation into a world-class facility on one site.  The main terminal is constructed over eight storeys, five above ground and three below, and is served by two satellite buildings, Terminal 5B and Terminal 5C.

Two air-side access tunnels (North and South) connect the new Satellite B and Satellite C buildings and go onward to the main T5A terminal. Their primary use is for the vehicular transport of disabled passengers and the movement of baggage between buildings. Whereas the North tunnel is flat the South tunnel is laid to a gradient of approximately 1:60. Both tunnels are over 400 metres long and 8 metres wide which posed significant delivery problems, the biggest of which was to successfully apply the “liquid” screed to the steep gradient of the South tunnel.

Carillion appointed The Progressive Group, Godstone, to design and deliver a flooring system to ensure the surface longevity of the connecting tunnels. “The logistics involved in trying to deliver and lay concrete to the work area was extremely difficult and we were made fully aware of both the problems encountered during the previous phase of T5A to Satellite B tunnel where the final finish was not satisfactory to BAA,” says David Timlin, manager, The Progressive Group.

The system proposed by Progressive was to install a heavy duty base screed topped with a high-strength industrial liquid levelling screed. This proposal was approved and technically supported by Saint-Gobain Weber and welcomed by the project architect, Peter Shelton, Pascall+Watson, who inspected a previous application of the same flooring system, also installed by Progressive, at King’s Cross underground station. weber.floor 4610 industry top as the finish screed achieved a durable, attractive and very hard wearing surface. It is a standard drying screed and can be applied in thicknesses of 4 – 15mm and has high compressive and flexural strength.  weber.floor 4610 industry top can take foot traffic within 2 – 4 hours of application and is fully cured after 7 days.

“Access to these tunnels was difficult, from one end only, and down three levels. We set up our pumping station outside Satellite C building and the pumping pipe run was over 250 metres. We then used electric barrows to get a further 200 metres for delivery,” says David Timlin.  “Following the installation of the fibre reinforced heavy duty screed over a 1000-guage separating membrane, we set out and accurately saw cut construction joints into the screed in 9m bays. One of our biggest challenges was to install the weber.floor 4610 industry top to the tunnel with the significant fall. By carefully controlling the mix and material consistency we reduced the “drag” factor to minimise movement of the material once it had been installed and levelled. Then we cut matching mastic joints in the weber.floor layer and achieved a superb final finish in both tunnels.”

Carillion and client BAA were delighted with the flooring solution designed by Progressive: “The programme was successfully completed in a difficult environment and the devised solution provided a great result for these walkways,” comments Marcus Luff, project manager, Carillion, Heathrow T5C.

The Progressive Group was ‘Winner of the Screeding Award for Heathrow T5C Tunnels’ in the 2011 Federation of Plastering & Drywall Contractors (FPDC) Plaisterers’ Awards.

Further information about weber.floor products is available from Saint-Gobain Weber on 08703 330 070, or 028 9335 2999 in Ireland, or visit netweber.co.uk and register to receive a copy of the Flooring Systems handbook.  A free download of the new weber.app for iPhone and iPad users is also available from the iTunes app store and from Google Play for smartphone and tablet users.