Project Description

A pumped storage hydro power station is to be built between the existing storage lakes Vieux-Emosson and Emosson. It is built in an underground cavern – one of the biggest in Europe. The cavern houses six Francis turbines with a total output of 900 MW. The power plant is located at the French-Swiss border amidst the Valais Alps. The construction work comprises a gigantic machine cavern, several smaller caverns, vertical shafts, water inlet- and outlet galleries, several kilometres of accessible gallery system and a raising of the Vieux-Emosson dam wall. The excavations have been carried out by both conventional and TBM. Once complete, the power station should produce 2.5 billion KWh/a power.

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Project requirements

Self Compacting Concrete (SCC ):
Final compressive strength: C30/37
Durability: XC2/XF1
Chloride class: 0.1
Consistency: Slump 750 mm
AAR: < 0.02%
Water penetration depth under pressure: < 25 mm

Compressive strength development: J2
Workability time: 2 hours
Final compressive strength: C30/37
Durability: XC3/XD1/XF3
Chlorid Klasse: 0.2
Consistency: AM 560 mm / pumpable
AAR: < 0.02%

Sika Solutions

After preliminary trials, Sika was able to offer tailor-made products for the concrete systems. The requirements on both, fresh and hardened concrete, have been quite demanding. The use of 100% excavation material as aggregates for the concrete was an added challenge for the fulfilment of this task. Sika impressed the contractor with different products, which enable the manufacturing of self-compacting and conventional cast-in-place concrete as well as project-specific special concrete. Also, the combination of shotcrete superplasticizer and alkali-free accelerator was a powerful package. The construction site was visited regularly by our technical personnel and Sika concrete service technicians carried out quality checks.