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Chapelcross Substation

Date - June/July 2018
Summary - A recently poured concrete bund structure failed as a result of significant uplift pressure due to the high water table level. This resulted in cracking of the concrete that subsequently provided a route for water to ingress.
Waterproof Tanking System Scotland
Waterproof Tanking System Scotland

Due to the potential of this situation re-occurring under significant water pressure, a scheme was developed to increase the weight loading over the original concrete structure by installing a secondary concrete slab across the surface. An opportunity was taken to install a waterproof tanking system to the bunded area prior to the installation of the additional concrete slab. This consisted of Sika Combiflex bandage to all construction joints and cracks, working against live water ingress utilising the Sika 4a fast cure Waterstop. The walls of the bund were overcoated with an epoxy bonded Sika 1 Pre-Bagged tanking system. The horizontal slab was overlaid with the Sikaproof A08 tanking membrane, lapped to the Sika 1 tanking with the Combiflex bandage.

Waterproof Tanking System Scotland
Waterproof Tanking System Scotland

With the waterproofing installed, we installed a designed mesh reinforcement layer, formed upstand concrete walls and infilled the full area with a waterproof concrete mix onto the Sikaproof A08. The concrete/Sika 1 render junction was additionally sealed with a fully bonded Sikaswell hydrophilic joint strip.


An area that was consistently flooded with in excess of 200mm of water over a 270m² area that ingressed over a very short period of time, is now fully waterproofed with no ingress.  

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