If the concrete cover over the steel is too thin, rust has an easy time.. At Sägestrasse 77 in Köniz, a classic renovation case presented itself: the damaged parking deck coating had allowed water and de-icing salts to deeply penetrate, leading to the corrosion of the reinforcement. Within five weeks, our team removed the damaged areas, protected the steel, and completely rebuilt the concrete surface.
Starting situation
Parking decks are heavily stressed in everyday life. Vehicles, moisture, and de-icing salts damage the surface over the years. If a coating is no longer waterproof, moisture can penetrate the concrete. It becomes particularly critical when chlorides reach the reinforcement. Corrosion then begins, and the supporting structure must be specifically protected.
The exact same situation was evident at the parking deck in Köniz. The existing coating had lost its protective function. In various places, the concrete cover over the reinforcement was too thin, and corroded reinforcement had to be replaced. At the same time, the slope needed to be adjusted to the existing structure to ensure proper water drainage in the future.
The goal was therefore clear: remove damaged areas, protect the reinforcement, and rebuild the concrete.
Demolition and ground preparation
First, the old coating was removed from approximately 250 square meters. This was followed by the damaged concrete: using ultra-high-pressure water jets, we removed 30 to 60 millimeters of material, down to the third reinforcement layer in some areas. Since the parking deck is located directly next to building entrances and a busy street, the work on-site required a lot of consideration and precise coordination. However, the high-pressure method has a big advantage: it selectively removes damaged material and preserves the remaining structure of the building. After removal, we cleaned and neutralized the exposed surface so that the new layers would adhere firmly to the substrate later.
36 tons of mortar and precise connections
As a base, we applied a one-component adhesion promoter and corrosion protection. It protects the exposed steel from new corrosion. We replaced the removed concrete with an R4 high-performance concrete repair mortar. This mortar contains plastic fibers, meets the requirements of damage class R4, and is produced with a reduced carbon footprint. In total, the team processed 36 tons of it in layers of 40 to 90 millimeters.
Since water needs to drain cleanly from a car park deck, we incorporated a new gradient of around 2 percent directly with the mortar. The actual challenge here was matching it to the existing structure. We had to precisely adapt the gradient to the existing gutters, drains, road surface, and the edge of the freight elevator. Ultimately, no tripping hazard should remain, and no water should accumulate.
Polyurea coating for parking deck Köniz using the hot spray process
First, an epoxy primer was applied to the repaired concrete. Pure polyurea then takes over protection against water and salt. We spray this liquid plastic onto the surface using the hot spray process. The material hardens within seconds, forming an elastic protective membrane without seams. With the variable spring weather, this rapid curing was an important factor in keeping to the schedule.
To prevent cars from slipping on the new surface, we incorporated aluminum oxide into the second layer. A final, robust top layer seals everything. After approximately five weeks of work, the parking deck of the condominium owners' association is fully available again, protected against moisture and salt. A great piece of work that our team is proud of.
