Eastern Tunnel, Storebelt (Great Belt Fixed Link), Denmark
Storebelt and Kattegat divides Denmark into two equal sized population blocks of 2.5 million each. To eliminate ferry traffic, a road and train connection has been built over Storebelt. There are three main elements to the crossing - the Eastern Tunnel, Eastern Bridge and Western Bridge.
The connection must maintain its serviceability with a minimum amount of maintenance and repair throughout the 21st century, which means the strictest requirements to materials and structural design. Elkem Microsilica was used to provide durability as part of a three-powder binder (in addition to cement and flyash), and to ensure fresh concrete properties.
The Laerdal Tunnel, Norway - the world's longest road tunnel
In June 1992 the Norwegian Parliament decided that the road between Bergen and Oslo should be built via Aurland, to Laerdal and over Filefjell. The 24.5 kilometre long road tunnel between Aurland and Laerdal represents the final link of the new main highway connecting Oslo and Bergen without ferries and difficult mountain crossings during the winter. The tunnel was opened in November 2000.
Schönrain Tunnel, Germany
The Schönrain tunnel is a 4 km long railway tunnel constructed for the German High Speed Train (HST). The tunnel has a width of 16 metre in order to accommodate two tracks and allow high speed trains to pass at combined speeds on the order of 500 km/hr without excessive ‘piston’ effects. The cross section of the tunnel is about 150 m2. The German Federal Rail Authority (Deutsche Bundesbahn) specified the use the dry shotcrete process for the tunnel lining. An important factor in the choice of a microsilica-based liner was the improved resistance to leaching caused by: reduced permeability, chemically bound calcium hydroxide, and a reduced need for accelerator.
Guldborgsund Sub-Sea Tunnel, Denmark
The Guldborgsund tunnel connects the islands Lolland and Falster in South Denmark. The tunnel is 460 metre long, and was built in two segments. These segments were cast in dry dock, floated to their positions and ballasted down. Elkem Microsilica was used in the second segment to improve the concrete properties in general. Higher concrete strength and better workability were the most important factors.
Building of the Guldborgsund tunnel was the last part of an express-way crossing Sjaelland (Zealand). It eliminates the use of ferries on the route from Helsingor to Roedbyhavn. The traffic can link to the European highway system by ferries between Roedbyhavn and Puttgarten in Germany. The tunnel segments, each 230 metre long, were cast in drydock. The construction work started in April 1985, and the tunnel was opened in June 1988.
The main concrete properties were strength, density and durability.
The construction was performed without any problems. The improvements to the mix design resulted in:
- Increased strength
- Stability of the air content
- Good workability
- Excellent concrete surface
- No cracks
- Less expensive concrete
The Singapore Mass Rapid Transport system
Consists of three main railway lines covering the island, North to South and East to West, that converge on the city itself. The MRT was built during the 1980s as part of the long term plan to control traffic congestion in the city centre. In 1986 three sections of MRT tunnel, totalling 2.4 km in length, were cast using microsilica concrete.
Among the benefits obtained were increased strength gain, increased impermeability and sulphate resistance, and improved plastic properties.