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The TENSA®POLYFLEX®ADVANCED (Type PU) joint, mageba’s top-of-the-range flexible plug joint, has been used to replace the many small-movement expansion joints of the Älvsborg Bridge in Gothenburg – thanks in part to the ease with which it can be installed in sections, lane by lane, with no loss of durability or performance.
When the Älvsborg Bridge in Sweden, built between 1963 and 1966 with a main span of length 417 m, required to have its many small-movement expansion joints replaced in the course of recent renovation works, an expansion joint solution that would reliably meet the project’s demanding requirements was needed. The bridge, which connects Gothenburg across a sea inlet for approximately 80,000 vehicles per day, is a critical structure for the whole region so it was essential that the new expansion joints could be installed with minimal impact on traffic, while also ensuring maximum durability to minimise the need for future repair or replacement work. In particular, it was necessary to choose a solution that would facilitate installation in phases, lane by lane, so that traffic could always flow on both sides of the bridge throughout the project.
Having already supplied a structural health monitoring (SHM) system for the bridge in 2011 to enable the movements of the bridge to be precisely evaluated, mageba was already very familiar with the structure and its needs, and well positioned to propose the optimal solution: the POLYFLEX®ADVANCED (Type PU) flexible plug expansion joint. This type of joint, a far superior alternative to the traditional asphaltic plug joint, can be used to replace any other type of small-movement joint with little or no impact on the main structure, forming a perfectly flat and continuous driving surface. The specially developed polyurethane material used offers extraordinary flexibility and durability – even being more durable than typical bituminous road surfacing in most cases. Its durability and functionality have been proven in extensive laboratory testing, resulting in the awarding in 2012 of a European Technical Approval with validity across the European Union and other EOTA member states such as Switzerland, Norway and Turkey.
Approximately 1500 m of the TENSA®POLYFLEX®ADVANCED joint, with a movement capacity of 30 mm and adapted to suit the bridge’s road surfacing depth of 65 mm, was supplied by mageba. This was installed by the contractor, under mageba supervision, at 26 bridge axes, with each joint installed in four sections to suit traffic phasing. Thanks to the PU material’s ability to reactivate, simply pouring fresh PU material at the end of a previously installed section forms a perfect bond between sections, ensuring optimal functionality and durability at these locations.
The installation of the expansion joints, carried out in conjunction with repaving of the bridge’s driving surface, has now been completed, and based on the positive experience to date, a further project has been agreed with the contractor and others are expected to follow – especially for refurbishment projects, where the PU joint’s flexibility in various ways is especially beneficial.
“The biggest challenge was the high volume of the required joints and the short construction time (2.5 weeks) to get all joints done. To accomplish this goal you need exact planning and a competent, reliable and flexible partner on the bridge.
mageba would like to take the opportunity to thank the whole team of the DAB Group – Sweden for their supportive cooperation!”
Dominik Ortmann, Product Manager TENSA®POLYFLEX®Advanced, mageba Austria
Bridge constructor: AB Armerad Betong/Friedrich Krupp
Refurbishment contractor: DAB Sweden
Bridge owner: City of Gothenburg
Installation of this expansion joint type on an existing bridge can be done with minimal impact on the structure – typically requiring the existing expansion joint to be removed only within the depth of typical bituminous road surfacing, creating a suitable surface to which the poured material can bond