The Ingeniero Fernández Casado Bridge near León in northern Spain was opened in 1983. At the time, it was the stay cable bridge with the world’s largest span. A total of 220 stay cables are attached at the two 102.3 and 117.3 m high, H-shaped pylons. The structure has lateral spans of 65 m and crosses the Barrios de Luna water reservoir with a 440 m long middle span.
Recently, the pipes of some stay cables were comprehensively rehabilitated. Cracks that had opened in the pipes were sealed, and some stay cables were wrapped using a corrosion protection tape system.
The stay cables of the Ingeniero Fernández Casado Bridge have diameters between140 and 225 mm and consist of 24 to 80 steel strands that are protected from corrosion by the enveloping cement mortar and PE ducts. During the course of the years, mechanical and climatic influences caused damage to the stay cables that was discovered by both a detailed visual stay cable inspection and an inspection using a drone.
Afterwards, the cracks in some of the cable pipes were repaired. In cases of larger damage, the respective pipe sections were replaced and the new sections welded on. The areas in which the stay cables had rusted were cleaned and additionally protected from corrosion. Following the repair work, the stay cables were wrapped with a protection tape.
The system is based on two multilayer tapes consisting each of a stabilized polyethylene carrier film with a coextruded butyl rubber layer. The tape is applied using a specific amount of pressure and an overlap of 50% in two layers, thus also permitting a radial mechanical strengthening of the duct.
The higher pylon areas were only accessible via ropes and platforms. On the lower 30 m, repair work was carried out from baskets. Furthermore, a robot was used for wrapping the stay cables with the “DYNA Protect®-System”.