Mapei delivers bespoke waterproofing solution at Bank Station

A Mapei waterproofing solution has been installed as part of London Underground’s Bank Station Capacity Upgrade to increase passenger capacity and provide step-free access.  The system - which included Mapegrout Gunite FSD and Mapelastic TU - was developed by Mapei’s Underground Technology Team (UTT) in collaboration with main contractor, Dragados; Transport for London and Engineers, Dr. Sauer & Partners.  It ensured that the new infrastructure was watertight, and maintained a safe and secure environment for passengers.

An ambitious and complex project, the Bank Station upgrade has increased the station’s capacity by 40%. It includes a new railway tunnel and wider southbound platform for the Northern line; step-free access to the Northern line for the first time and improved step-free access to the DLR platforms; new station entrances and interchange routes, moving walkways, lifts and escalators, and approximately 1400 metres of new tunnels. The installation, by Dragados, spanned a tunnel surface of approx. 24,000m2; it featured a low dust regulating layer of Mapegrout Gunite FSD and spray-applied of Mapelastic TU. The system was also used to waterproof reinforced concrete works in areas including shafts.

Mapegrout Gunite FSD is a fast-setting, ready-to-use fibre-reinforced cementitious mortar developed for concrete, stone and masonry structures including tunnel linings, shafts and foundations. It provides excellent bonding strength and speed of application, with low dust emissions. Waterproofing membrane, Mapelastic TU system is a one-component ready to use sprayable synthetic membrane developed for tunnels and underground structure waterproofing. Featuring excellent tensile strength and adhesive properties, the membrane creates a flexible, seamless waterproofing barrier and can be used in new tunnels and to replace existing systems. Other Mapei products specified included two fast drying hydraulic binders – Lamposilex, a water plug and Topcem for screeds – and two paint finishes: Silexcolor – a silicate based, vapour-permeable protective paint - and Mapecoat ACT – a mould, virus and bacteria-resistant cleanable enamel paint.

Throughout the project, Mapei UTT provided technical support and training to ensure the project's unique challenges were met. The system accommodated heavy reinforcement, restricted access and low temperatures and the dust-free application – which was recognised in the NCE Tunnelling Award received by Mapei UTT – ensured a safe application in a challenging environment. 

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