Kanderviadukt: durability and speed of execution


A new life for an emblematic structure! The Kanderviadukt was stabilised using a protective coat of Ductal®.


Built in 1911 at Frutigen, on the Lötschberg line, the Kanderviadukt is an emblematic structure in the valley. This stone masonry bridge, 274 m long, acts as a link between the north and south of Europe for the transport of people and goods.

During regular inspections of the structure, it was discovered that the polymer bitumen sealing (PBD), applied sixty years before, was no longer able to protect the structure against water infiltration resulting in the first damage to be suffered by the bridge. A new protection was required in order to guarantee its integrity for the coming decades. The engineering company in charge of this project therefore proposed a like-for-like replacement of the PBD coat as well as a variant in Ductal® ultra-high performance fibre-reinforced concrete (UHPFRC).

As this was the first time the project owner had dealt with this type of material, the variants were studied at length to compare their respective added values. The final choice was based on the solution using UHPFRC.

Kander Viaduct, Frutigen, Switzerland (Courtesy of B+S AG)



A material suited to railway structures

The extremely dense matrix of Ductal® UHPFRC not only guarantees that the 30 mm layer poured onto the bridge is completely weaterproof, but has a very high mechanical performance thus avoiding the need to protect the sealing layer. As the installation of UHPFRC is only marginally dependant on weather conditions, execution lead times, very important in the rail transport sector, may be guaranteed and the total duration of projects is often shortened. The durability of the material avoids the need to replace the sealing up to the end of the life of the supporting structure which reduces maintenance costs and costs associated with line closures.

A complete protective layer

30 mm of Ductal® was poured onto the whole of the upper section of the trough. A liquid formulation was used to fill the edge formwork while a firmer formulation, taking the slope into account, was poured onto the deck and the horizontal section at the top of the edging pieces. The whole of the exposed part of the bridge was thus protected against water infiltration. The condition of the supporting concrete was significantly worse than predicted, but the solution of Ductal® UHPFRC enabled the work to be finished on time, especially with the whole of the horizontal surface being poured in a single day. Pouring in a single step in this way also avoided having joins in the section where water runs off into the drainage systems.

A solution to inspire others

For a structure on such a scale, the question of cost is clearly high on the agenda. The UHPFRC solution provides a more durable structure and limits the need for future maintenance work. The ability to guarantee deadlines was also a determining factor in the project owner's choice, all the more so since the Ductal® UHPFRC variant studied added only 1% to the total cost of the project.

This type of project allows project owners to use the properties of UHPFRC to best advantage, to limit costs over the lifetime of the structure and limit the impact on the user by reducing the time needed for closures due to the works.

Other rail project owners, such as CFF and the SZU have already put their trust in Ductal® for their projects and will give priority to our solutions for their upcoming works.

Kander Viaduct, Frutigen, Switzerland  (Courtesy of B+S AG)



Similar references

SBB        Bachdurchlass Immensee – Arth/Goldau

SZU        Mühlebachbrücke – Brienz

SZU        Lammbachbrücke – Brienz 

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Works stakeholders

Project owner: BLS

Works management: B+S AG

Company:  Walo Bertschinger

UHPFRC:  Ductal® de LafargeHolcim

Kander Viaduct, Frutigen, Switzerland (Courtesy of B+S AG)



Our services

  • Development of special formulae for sections using formwork and on a slope using the same basic material
  • Just-in-time delivery of Ductal® given the cramped conditions on the jobsite
  • Advice on the material and technical follow-up of the project

Ductal®’s innovative bridge overlay system not only protects bridge decks, but improves its structural performance with a cost-effective long-term solution.