Pioneering in underwater tunnel support
A new rail tunnel is being constructed under the River Scheldt to provide additional access to the increasing cargo traffic in and out of the port of Antwerp (Belgium). Once completed in 2014, the tunnel will be a historic first, as it is extremely close to the bed of the Kanaaldok port terminal. Since pushing the limits of tunnel construction means deploying the best technology available, Bekaert was glad to contribute to this challenging project.
Steel fiber reinforced concrete for safety
This particular tunnel called for the use of a huge concrete slab as protection during the drilling process. According to Locobouw1 , the main contractor, the concrete ‘floor’ will prevent overpressure from escaping to the surface, which could otherwise cause a collapse. In addition, it will protect the tunnel from damage when ships anchor in the port waters above.
To construct this 2 meters thick, 32 meters wide and 270 meters long fiber reinforced concrete slab, Bekaert offered an integrated solution with at its core 600 tons of Dramix® steel fibers and all the dosage equipment to cast it according to specifications and within a tight timeframe.
Short timeframe for a challenging job
Since no reinforcement cages or mesh could be used and the concrete slab had to be one solid, monolithic structure, ensuring a continuous flow of concrete during the casting process was crucial to success. Timing was another important issue: traffic at this location in the Antwerp port could only be halted temporarily. So, the casting had to be completed in a minimum of time.
Bekaert lives up to high standards
Locobouw selected Bekaert and its Dramix® steel fibers based on strenuous testing at the technical university of Braunschweig (Germany). We were the only supplier of steel fiber to live up to the high standards set for this challenging project. Bekaert was also the only bidder capable of providing the right kind and numbers of automatic dosage equipment to ensure a continuous flow of steel reinforced concrete.
1 Temporary association of MBG, CEI De Meyer, VINCI Construction Grands Projects and Wayss & Freytag
Furthermore, DCN Diving, the company in charge of the underwater activities, preferred to work with steel fiber reinforced concrete as it significantly increases operating speed and safety compared to reinforcement cages.
Our totally integrated solution guaranteed the automatic lowest possible dosage of the steel fibers, and a perfect spread in the concrete mixture as a result. Our 24h technical assistance and the availability of spare parts and backup personnel were key to rounding off the project on time and in conformity with the high quality standards. Bekaert also advised on adjusting the concrete pumps to ensure smooth pumping.
Putting our knowhow to future use
From left to right: Arnold Roos (Locobouw), Geert Bettens (Bekaert) and Wim Vriens (DCN Diving)
“Reliability is key in the underwater pumping of steel fiber reinforced concrete. Our divers need to be sure that the product is easily pumpable and does not cause lump formation. That is why we prefer the glued concept of Dramix®”. Wim Vriens, Director of Operations, DCN Diving
Our experience with the long-distance pumping of steel fiber reinforced concrete in the Liefkenshoek rail tunnel project was essential in the success of another major project in tunnel construction, this time in the rail link with Brussels Airport (Belgium).
In the near future, we will again partner up with DCN for a concrete casting project at an underwater location in Utrecht (the Netherlands), once more putting into practice our better together philosophy.