Project Reports: Crack Repair

Injection of Expansion Joints and Cracks in Hellberg Tunnel

The roughly 160 meter long road tunnel was built as part of the Kirn ring road in the course of the B41 in the early 1960s. Over 9,000 vehicles are using this connection every day. Fundamental repair due to wear was therefore urgently required. The 'Landesbetrieb Straßen und Verkehr Rheinland Pfalz' and the Driver and Vehicle Licensing Agency of Bad Kreuznach commissioned the BWS Rhein-Neckar company with this task.
The extensive concrete repair work began in July 2007 and took almost 11 months. During this period traffic had to be directed towards Kirn in a single lane past the road works. After partly exposing the concrete finish it was determined in accordance with the Additional Technical Terms of Contract and Guidelines for Civil Engineering Structures ('ZTV-Ing') how to position the drill holes for crack injection.
After making the drill holes and setting the packers, waterbearing cracks were first closed with the quick-curing, moisture-reactive PU Injection Foam Resin WEBAC®150. The injection was then carried out in order to durably seal the 0.2 – 1.0 mm wide cracks with the PU Injection Foam Resin WEBAC®1405. This injection resin is characterized by its very good edge adhesion and expandability, which ensures long-term tightness even if structural components are exposed to high stress levels.
In the course of the concrete repair work it was not an easy task to restore the sealing function in the area of the expansion joints. Thanks to the excellent material properties such as high expandability and strength it was decided to use Injection Gel WEBAC®240 for this purpose. The gel was injected according to the specifications in the building plan. The injection was carried out by means of a 2-component pump with pressure limit and a measuring unit for automatically recording the flow rates.
The work was performed and supervised in accordance with the specifications of DB Directive 804.6102.
Thanks to the WEBAC® products used, the reconstructed tunnel is now just like new, fit for the future and will once again fulfill its function of easing traffic in the town of Kirn in the decades to come.