20,000 m² office space successfully sealed off
The construction of the office building OSCK Venice in Prague was finished in 1998/99. The subterranean level of the building, mainly used as an underground garage, lies approx. 8 m below the watertable. As a barrier against water penetrating from the surrounding grounds, the exterior walls on that level were covered by a water-proof PVC foil on the outside.
Once the building was erected and the pumping off of the groundwater stopped, the PVC foil showed signs of extensive leaking. It became apparent that all sub-terranean construction joints of the rooms that had not been sealed off, were holding water.
The problem of constructing an effective post-con-struction water stop, was solved in the following way:
Without damaging the underlying PVC foil, the concrete ground was perforated at 1 m intervals along all affected construction joints. Via injection packers, PU injection foam resin WEBAC® 151 was injected, followed by PU injection resin WEBAC® 1403. By this procedure, individual squares could be separated from each other in an overall area of approx. 50 m². The water pressure in each field could thus be measured independently to establish if the PVC foil was damaged at that particular point. Wherever a leak was detected, the field in question was filled with WEBAC® 151 and WEBAC® 1403.
In the course of one year and with an estimated 20 tons of WEBAC PU injection resin, it was possible to successfully seal off 20,000 m².