Essential contribution of BASF construction chemicals to build the Gotthard Base Tunnel
BASF concrete admixtures optimize ways of using concrete under the special conditions of underground works.
MEYCO® Fireshield 1350 fire protection mortar protects the final concrete lining of the Bodio tunnel section from excessive heat.
October 15 will see the main breakthrough between Faido and Sedrun along the eastern tube of the Gotthard Base Tunnel. During the construction of the longest railway tunnel in the world, the use of construction chemicals supplied by BASF has been essential to ensure efficiency, durability, safety and a sustainable approach to construction.
BASF has supplied concrete admixtures, concrete spraying machines and fire protection mortar for two of five construction sections, around 20 km of the total tunnel length (57 km).
In the section between Erstfeld and Sedrun, concrete admixtures supplied by BASF have been used for construction of the tunnel lining of the two parallel tunnel tubes and the cross passages that connect the tubes every 300 meters.
“When used for underground work, concrete must meet the most contradictory requirements: when being transported over several kilometers into the mountain it is essential that the concrete does not harden and that it continues to be workable for hours. As far as the Gotthard Tunnel is concerned, this is one of the greatest challenges. On the other hand, the concrete must solidify in a flash as soon as it is applied to the tunnel wall,” says André Germann, Manager of MEYCO Underground Construction for Germany, Austria, Switzerland and Eastern Europe.
This is made possible only by using the correct combination of concrete admixtures: various superplasticizers sold under the GLENIUM® brand make concrete especially free flowing. The MEYCO® SA 160 accelerator for sprayed concrete on the other hand ensures that concrete, once applied to the tunnel wall, solidifies in seconds.
In order to meet the special challenges concerning the processability of concrete in the Gotthard Base Tunnel, BASF has developed the DELVO® Crete Stabilizer 10. This admixture slows down cement hydration and ensures an open time of four to six hours. Combined with the GLENIUM® superplasticizers, the concrete can be used perfectly well even when being transported over long distances and exposed to the high temperatures in the interior of the mountain. In the Gotthard Base Tunnel, this system combining superplasticizers with retarding agents has been used for initial securing measures after excavation as well as during the concreting of the inner shell.
In addition, BASF’s MEYCO® machines MEYCO® Potenza and MEYCO® Oruga concrete spraying units were used in the two construction sections between Erstfeld and Sedrun, in the northern part of the tunnel, for construction of the primary tunnel lining (reinforced sprayed concrete) just after excavation of individual tunnel sections by the tunnel boring machine (TBM). These special machines have been developed to cope with the difficult conditions during tunnel construction. By means of MEYCO® Potenza and MEYCO® Oruga spraying units concrete was applied quickly onto the excavation surface immediately after removal of excavation material, enabling rapid building of excavation support and safety of working crew.
Further, the MEYCO® Fireshield 1350 fire protection mortar manufactured by BASF protects the concrete tunnel lining of the Bodio tunnel section near the southern entrance of the tunnel against excessive heat in the case of fire. Application of this special fire protection mortar was required, since temperatures exceeding around 300 degree Celsius lead to concrete crumbling, and when concrete is exposed to temperatures above 1,000 degree Celsius it loses its load-bearing capacity altogether and the tunnel may collapse.
“Being covered with a layer of fire protection mortar the tunnel walls withstand temperatures of up to 1,400 degree Celsius for a minimum of 90 minutes. This way we gain some precious time for firefighting,” says Frank Clement, BASF expert for underground fire protection solutions.
BASF’s MEYCO® Suprema spraying unit and the MEYCO nozzle system, which is specifically adapted to fire protection mortar, were used to apply a layer of a specified thickness onto the inner concrete lining of the tunnel.
From 2017 onwards, the Gotthard Base Tunnel will shorten the traveling time between Zurich and Milano by one hour. In addition, freight trains will be able to travel with twice the load and speed due to the track’s lesser incline. This means that people and goods will be able to cross the Alps faster, more safely and in a more environmentally friendly way.
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About the Construction Chemicals division
The Construction Chemicals division is the leading supplier of chemical
systems and formulations for customers in the construction industry. Due to continuous innovation and tailor-made solutions the division ensures that its customers are more successful. Its Admixture Systems business unit helps customers in the ready-mix, precast, manufactured concrete and underground construction industries. The Construction Systems business unit offers a wide range of products for sports and industrial flooring, wall insulation and external rendering systems, expansion joints, wood preservatives as well as finishing products such as mortar, repair mortars, tile adhesives and waterproofing systems. The division operates production sites and sales centers in more than 50 countries and achieved sales of around €2 billion with approximately 7,100 employees in 2009.
About BASF
BASF is the world’s leading chemical company: The Chemical Company. Its portfolio ranges from chemicals, plastics and performance products to agricultural products, fine chemicals and oil and gas. As a reliable partner BASF creates chemistry to help its customers in virtually all industries to be more successful. With its high-value products and intelligent solutions, BASF plays an important role in finding answers to global challenges such as climate protection, energy efficiency, nutrition and mobility. BASF posted sales of more than €50billion in 2009 and had approximately 105,000 employees as of the end of the year. Further information on BASF is available on the Internet at