Upgrading of substructure 3 UF Nidda near Frankfurt

The structure consists of a total of three substructures, which were built between 1960 and 1970 as a 5-span prestressed concrete bridge with a 2-web plate girder with a total length of 79 meters. Sigma Oval prestressing steel, which is prone to stress cracking, was used for longitudinal prestressing.

In 2020, two of the three substructures were successfully repaired and reinforced with carbon concrete in the area of the superstructure and on the undersides of the footbridge. The A648 UF Nidda consortium was commissioned to repair the last substructure, substructure 3, with the participation of ZÜBLIN Bauwerkserhaltung.

A tent on the highway

At the start of construction in July, a full road closure was set up on the section of the structure to be renovated and traffic was diverted to the two neighboring structures. The old asphalt pavement, including the seal, was removed by milling between the caps. The upper part of the concrete was then removed and the superstructure was roughened using ultra-high-pressure water jets. A tent with three air conditioning units was erected along the entire length of the bridge to provide sun and weather protection for the reinforcement work.

The carbon concrete was installed by spray application in five layers. The reinforcement was carried out with textile reinforcement type SITgrid 040 and embedded in a fine concrete type Pagel TF10 in accordance with the general building authority approval for textile concrete (TUDALIT). In the following days, the waterproofing was applied and the mastic asphalt was laid.