Masonry Problem

Restek were invited to visit a site in Canning Town, East London to advise the current contractor on methods to alleviate leaking to a subway alteration project. The project comprised breaking into an existing subway and forming an access ramp on a right angle to the existing structure.

Caltite concrete had been used for the alterations with a 25mm wide expansion joint using Korkpak filler board and a serviced external water-bar. After the pumps were removed, water began to leak uncontrollably from the horizontal and vertical expansion joints. A method had to be devised to both seal the water ingress while maintaining the flexibility of the expansion joint.

Further Inspection

On further inspection, it also became apparent that the Caltite concrete used for the new structure had been displaying signs of micro cracking, highlighted once the pumps diverting water away from the subway had been turned off. The head of water then increased displaying water ingress from these barely visible fractures to the concrete and at day joints in the structure despite the installation of a hydrophilic water bar during construction.

Due to this, we had to come up with a solution that could not just water proof the subway externally but also stabilise these fractures and prevent any further decay of the building component. In time, large and small leaks formed endangered the walkways stability, so an extensive reconstruction considering the following boundary conditions was necessary in order to maintain the subways function.

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