Essential contribution of BASF construction chemicals to build Gotthard tunnel
* BASF concrete admixtures optimize ways of using concrete underground
* Fire protection mortar of BASF increases safety in tunnels
Ludwigshafen , Germany – October 15 will see the main breakthrough between Faido and Sedrun in Switzerland 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 been supplying concrete admixtures, concrete spraying machines and fire protection mortar for two of the five construction sections and for around 20 of the 57 kilometers covered by the tunnel.
In the section between Erstfeld and Sedrun, concrete admixtures supplied by BASF are used for 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 Underground Construction for Germany, Austria, Switzerland and Eastern Europe.
This is made possible only by using the correct combination of BASF concrete admixtures: superplasticizers make concrete especially free flowing. An 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 Tunnel, BASF has developed an admixture. It slows down cement hydration. Combined with the BASF 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 Tunnel, this system combining fluxing 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 concrete spraying machines are being used in the Gotthard Tunnel. The special machinery has been developed to cope with the difficult conditions during tunnel construction. Immediately after the removal of the rock these units spray concrete onto the tunnel walls, which prevents any further loosening of stones and ensures that water does not enter the tunnel.
To ensure that the tunnel walls near the southern entrance are protected in the case of a fire, they have been treated with special fire protection mortar. “Being covered with this layer 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.
From 2017 onwards, the railway 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.
Press photos are available at www.basf.com/pressphoto-database under the keyword “tunnel construction” or by entering the search term “Gotthard”.
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.
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 €50 billion 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 www.basf.com.
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