Accounting of Fly Ash for the Exposition Class XF2 - Tunnel Concretes

Project Number 225

According to the DIN 1045-2 07.01, the accounting of fly ash towards the aquivalent water cement value of concretes of the exposition class XF2 is currently not allowed. In practice, the above mentioned kind of concretes are used in the entrance area of the tunnel inner shells, which however, in single cases, requires the permission of the construction monitoring authorities in charge of the responsible state. In case of a permission for a reference project, the registration of a corresponding paragraph in the index for new tunnel buildings is possible.

The examination shall basically deliver findings about the freeze thaw and deicing salt resistance in the exposition class XF2. Thus, focus is on the determination of the freeze thaw and deicing salt resistance at the age of 56 days. Furthermore, the critical degree of saturation of concretes has to be determined. The temporal development of the pressure and crackile tensile strength of the concretes after a standard storage will be registered at the same time as the durability studies.

The realisation of the examination programme allows an evaluation of the accounting of fly ashes for the exposition class XF2 according to DIN 1045-2 07.01, particularly in concrete for tunnel inner shells in the entrance area.

Under the management of Professor Brameshuber the project is to be carried out between July 2002 and September 2003 at the building research institute, Technical University in Aachen. The Working Panel "Power Plant By-products" is supporting the examination technically.