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Precisely orchestrated concreting
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Precisely orchestrated concreting
The pace has quickened on the Hosingen cut-and-cover construction site. Since the end of January, our teams have been concreting the vaults of this structure, which is part of the project to bypass the town. This is both a technical and logistical operation, managed with great precision.
After a gigantic earthmoving phase, the way is now clear for the construction of the cut-and-cover section of the future Hosingen bypass. Since September 2023, a total of 420,000 m2 of material has been excavated, reaching depths of up to 25 m, to accommodate the 350 m-long structure comprising two traffic tubes, each around 8 m high.
A steady pace
The concreting phase, launched at the end of January, represents an important stage. Because of the double vault that characterises the structure, assembling the reinforcement is particularly complex. Using a formwork carriage, the concrete is poured in 27 segments of 12.5 metres each, at a sustained rate of six days per segment. ‘Each phase begins with two days of reinforcement, for which we have optimised the process by manufacturing the rebars on site,’ explains Romain Bodson, assistant site manager. This is followed by formwork, then concreting every Friday. After 24 hours, the element is removed from the formwork, the carriage is moved and the cycle starts all over again. At the same time, we continue to build the foundations and walls of the trench. Particular attention is also paid to the ends of the tunnel, which will remain visible once the structure is complete. ‘These parts include sloping caps and an arch, which required very careful carpentry work for the formwork,’ he explains.
Tailor-made concrete
Concreting of the vault is scheduled for completion in October 2025.
Each phase requires 320 m3 of high-performance concrete, specially designed with our supplier. Its formulation includes fibres and guarantees its stability in the event of fire. The winter conditions also meant that adaptations had to be made to ensure that the concrete set properly. ‘We installed heating units under the formwork and used a curing trolley to apply an insulating layer immediately after stripping the formwork,’ adds our assistant site manager.
