ABSTRACT
The geological conditions at the Brenner Base Tunnel, combined with durable tunnel design and service life of 200 years require in special tunnel sections a high strength concrete C40/50 for the inner linings. Additionally to increased compressive strength, the concrete had to combine partially opposing requirements. These requirements include a good workability of fresh concrete, an increased fire protection by microfibers, an unerring achievement of required strength class C40/50, compliance with a maximum component temperature, slow heat development for internal stresses reduction, rapid strength development for a short stripping time and achieving frost resistance concrete close to the portal. In this contribution a new concrete concept is introduced. It focuses on three essential aspects: a) formulation of concrete, b) defining fresh concrete requirements, c) post-treatment to ensure crack prevention. Most important part of the concrete concept was the development of binder concept to combine contradictory requirements by using two certified binders with different, characteristic properties.
