Infrastructure Reference Project - Renovation of the Rendsburg Canal Tunnel
The Rendsburg Underwater Tunnel, which consists of two 640-meter-long tubes, was seriously damaged through chlorides contained in road salt. A number of Sika products were used in the renovation of the tunnel, including a high-grade dry-spraying mortar that also satisfies fire-resistance requirements.
Reinforced concrete has excellent qualities that make it indispensable in construction. External influences such as aggressive substances can cause considerable damage. For instance, over time, the chlorides contained in road salt seriously damaged the walls and carriageway of the Rendsburg underwater tunnel, which opened for traffic in 1961. The road salt carried in by the tens of thousands of vehicles crossing in the winter months penetrated its two 640-meter-long tubes. In its capacity as a client, Germany’s Federal Waterways and Shipping Agency decided to refurbish the tunnel for the long term using a special procedure: cathodic corrosion protection. Cathodic corrosion protection is a renovation technique whereby the current from an impressed current system or galvanic anode is used to protect structures from corrosion. Sika’s portfolio comprises a number of products that are ideally suited as a repair mortar and anode embedment mortar for this application.
Several Sika solutions were used in the refurbishment work, including SikaCem®Gunit®-212 SF, a high-grade dry-spraying mortar. This is one of the few products on the market that is approved for installing anode gates with this special corrosion protection technique and, at the same time, possesses the high fire resistance class required for tunnels. The successful project could help cathodic corrosion protection gain in popularity in Germany – opening up corresponding opportunities for Sika.