Isar Bridge Achering

Project description

Near Munich‘s Franz-Josef-Strauss Airport, the A92 Motorway crosses over the River Isar. The bridge was equipped with four single gap expansion joints. Due to its proximity to the town of Achering, the joints were fitted with noise-reducing elements on the surface to reduce the impact of noise on residents.

Delivered products

During an inspection of the expansion joints, leaks were detected. By means of the latest development, the patented sealant ROBO®SEAL, the installed joints were made watertight without any impact on traffic. Threaded holes, drilled from below, allow ROBO®SEAL to be injected directly into the clamp recess using a specially developed injection pump. ROBO®SEAL is a hydrophilic hydrogel on an acrylate basis. In contact with water it swells, increasing its volume. In this way, the sealant ensures 100 % watertightness of the expansion joint. The highly fluid characteristic of the fresh sealant enables it to fill out even the smallest recesses and effectively displace any existing water. Further corrosion is prohibited as the clamp recess is sealed both water- and airtight, preventing further damage. ROBO®SEAL can be used to ensure complete watertightness on any expansion joint which features elastomeric profiles clamped in the recesses of bordering steel profiles, and can be applied either in the factory before the delivery of new joints, or subsequently, as in this case, to make an existing expansion joint watertight.


The underside of a joint following injection of ROBO®SEAL


Installed expansion joint with surface designed to resist snow plough damage

Key Data




max. movement range 65 mm




Prestressed concrete bridge