The constant entry of de-icing salt in winter through the parked vehicles led to severe corrosion with pitting, especially in the area of the upper frame reinforcement.
The “Altes Haus” underground car park is part of a hotel and business complex. It is a heavily frequented inner city car park (Anselment system) from 1964. The third basement is in the area of the groundwater table.
The chloride-induced corrosion in the underground car park led to significant cross-sectional losses of the reinforcing steel inserted.
Extensive or even complete removal of the contaminated concrete was not economically feasible for reasons of stability. The static reserves of the corroded reinforcement were sufficient or were supplemented. In order to be able to rule out further damage in the future, the repair principle "K" (corrosion protection) was chosen. The chloride-contaminated concrete can largely remain in the structure.
As an anode system, a titanium system in the form of titanium strip anodes was laid horizontally on the wall and support base on the surfaces due to the high current capacity in combination with a long service life and high resistance to chlorides.