Carbonation of concrete causes corrosive damage that then leads to concrete spalling. This problem occurs with increasing frequency in parking garages. It can be traced to various causes and can permanently damage the building's statics. An early response in the form of professional renovation can avert subsequent damage to existing structures before the building's statics are irreversibly damaged and costly reinforcements of the supporting structure become inevitable. The Weiss+Appetito Group has the know-how and experienced staff as well as the machinery and equipment required to deal with both issues, and we support our customers by offering advice at an early stage of the process and then executing the required work.
Covered parking garages must meet various requirements and withstand high usage over long durations. De-icing salts introduced by vehicles as well as exhaust gases cause carbonation of the concrete that, sooner or later, leads to corrosion of the armouring. The Migros supermarket in Chly Wabere and the Coop branch in Biberist found themselves facing this problem, so they engaged Weiss+Appetito to implement sustainable cathodic corrosion protection (CCP for short). The first step in the CCP reconditioning process is to mill off the damaged concrete down to the armouring, which is then treated with an anti-corrosion product. Following this step, the cathodic corrosion protection (CCP) system is applied. A network of strip anodes is installed throughout the area of the parking hall that is connected via a rectifier to the cathode (the iron armouring). This creates a flow of electrons that protects the armouring and the concrete against contamination by chlorides, thus also preventing corrosion. A mortar system tested for class R4 compliance is then installed to level the surface. From this point onwards, there were some interesting differences between the two projects (Coop Biberist and Migros Chly Wabere). In each case, our specialists had to adapt the covering of mortar – which was now applied over the anode network – to accommodate the floor conditions.
It was possible to continue using the standard low-viscosity R4 reprofiling mortar in the Migros Chly Wabere project, but conditions at Coop Biberist required a mortar with higher viscosity because there was no gradient on the existing base plate. The ideal choice and the most cost-effective solution in this case was Tanarit AM 2000, a proprietary product of Weiss+Appetito AG. A gradient with evaporation channels was installed when this coating was applied.
An OS-tested parking deck coating was applied as the top layer. Available in all colours, this product offers protection for many years and enhances the aesthetic appearance of the covering. As part of the Coop parking garage project, the joints were also renovated and replaced with high-resistance Quiflex liquid joints at the same time. Both projects were undertaken without interruption to the retail trade operations and with minimal restrictions on customer traffic. The CCP system can be executed without major vibrations or noise emissions – major benefits as compared to conventional concrete reconditioning methods. Thanks to extensive preparations and appropriate flexibility on the part of Weiss+Appetito AG, the project was completed on schedule and in top quality.
A great future lies ahead for concrete reconditioning and renovation with the CCP system, but these techniques can also be applied as preventive measures in new buildings.