Application of steel fibre concrete for underwater concrete slabs

Abstract

In the heart of Berlin, the area of the Potsdamer Platz is being developed into a new multi-functional town centre. As most of the buildings reach far below the ground-water level, the construction of deep building pits becomes necessary. Due to special underground conditions and environmental protection requirements, sealing injection layers cannot be carried out for the deeper parts of these building pits. The remaining solution is to erect an underwater concrete slab, back-anchored by tension piles. These building pits are of a very irregular shape with extremely high water pressure on the concrete slab. In order to increase the overall safety of this construction, steel fibre concrete instead of plain concrete was used for these slabs, thus leading to a robust and ductile construction. This paper gives a short description of the building method, the tests carried out concerning the load carrying and deformation behaviour of such a slab and the additional tests undertaken on the building site to solve remaining questions about the underwater concreting technology of steel fibre concrete.