Our colloidal silica post-placement pozzolan (P3) technology proved to be the best solution for stopping water seepage into lift shafts at the new purpose designed Netcare Alberton Hospital in Johannesburg, Gauteng.
The eight lift shafts are in an area with a very shallow water table. Water would, therefore, seep from the bottom of the lift pits and opposite sides, flooding the shafts at a rapid rate. As fast as the water was pumped out of the shafts, they would fill up again.
We suggested SCP 743 because it is ideally suited for use on existing concrete. In this case, the concrete was nine months old.
Citi-Con, a leading waterproofing and construction surgery specialist, was appointed by Trencon, the principal contractor that was constructing the new hospital, to implement the solution.
Citi-Con first washed the walls of the shaft with a high-pressure water spray. It then closed all the areas from where water was leaking with cementitious plugs. Next, a 45° fillet was installed in the lift pits to seal the wall to floor joint. This was followed by the treatment of the walls and lift pits with colloidal silica post-placement pozzolan (P3) technology.
SCP penetrates at least 38mm within the pore structures of the concrete. It then reacts with available Calcium Hydroxide providing a longer Calcium Silicate Hydrate (C-S-H) chain. Once this reaction has taken place, SCP fills the capillaries as opposed to blocking them.
This one-time treatment successfully stopped seepage through the ground and opposite sides of the shafts.
“SCP proved to be a very effective solution for this application. There has not been a single failure since the solution was implemented and I, therefore, continue to use it in other similar applications,” Andre Vermeulen, Managing Director of Citi-Con, says.