Branich Tunnel – Aggregates assure Reaction Capacity at below-zero Temperatures
Since December 2011, construction work on the 1.8 km long Branich Tunnel has been forging ahead much to the delight of local residents of Schriesheim in Baden. 1,000 of the 1,800 m had been completed in late January 2013. The breakthrough will probably follow in June 2013. The tunnel is part of the “Schriesheim Bypass” project. The L536 is being upgraded over a length of 3.3 km. The Land of Baden-Württemberg represented by the administrative district of Karlsruhe is investing some € 85 million for the work to be carried out with around € 58 million accounted for by the Branich Tunnel.
The tunnel is being driven by trenchless means. In addition to the pure tunnelling activities, 5 emergency exits are being set up, which lead into 2 separate evacuation tunnels.
The construction work has gone down well with the population because a survey showed that the scheme would result in traffic in the old part of Schriesheim being reduced by almost 70 %. The obvious advantages for local residents in Schriesheim and outstanding cooperation with the responsible contractor Züblin, Stuttgart prompted the tunnel’s sponsor Brigit Ibach-Höfer at last year’s St. Barbara ceremony to speak of a familiar relationship between the citizens of the town and the construction workers on-site.
For preparing the concrete 390 kg CEM II 52.5 N Dyckerhoff, Amöneburg, shotcrete quality C 30/27 was used. The fresh concrete is delivered to the construction site by 3 different ready-mixed concrete plants (TB Kurpfalzbeton, TB Kühner and TB Leutershausen).
Hard frost prevailed particularly during the initial stages. Notwithstanding the products from the Gecedral® 100 range from Messrs. BK Giulini GmbH, Ludwigshafen/D assured the shotcrete’s reaction capacity even at these sub-zero temperatures. As a result the driving operations were able to progress quickly in spite of the inclement weather conditions; early strength class J 2 was attained without difficulty and safety during the excavation was assured all the time.