Transportprozesse im Beton bei hohen Temperaturen

01.01.2004 - 31.12.2006
Research funding project
Within the research cooperation on "High temperature effects on cement-based materials" between the Institute for Mechanics of Materials and Structures and Prof. Schneider, TU Wien, and Prof. Willam, University of Colerado, Boulder, transport processes and chemical reactions in concrete subjected to high temperatures, such as the evaporation of capillary and chemically-bound water, will be investigated. In case the permeability of concrete is not sufficient to allow the transport of the evaporated water to the free surfaces, the pressure build-up in the pore space may exceed the tensile strength of concrete and cause spalling. This type of concrete failure was observed during recent fire accidents in European tunnels (Montblanc tunnel, Eurotunnel, Tauern tunnel, ¿). The spalling depth reached almost 50% of the tunnel lining, requiring long and extensive reconstruction work. Moreover, the reduction of the thickness of the concrete lining by 50% and the dehydration of cement taking place in the remaining 50% of the lining results in a severe reduction of the safety of the tunnel. This was the motivation for the initiation of several, so far experimental, research projects throughout Europe. In Austria, a research project titled "Fire resistance of fibre-, reinforced-, and prestressed concrete" was concerned with the experimental investigation of spalling for different designs of tunnel-linings. The obtained results showed that the increase of the amount of polypropylene (PP) fibers resulted in a decrease of spalling. By adding PP-fibres, spalling was reduced from originally 25 cm to 5 cm for 1.5 kg fibers/m3 concrete and to few millimetres for 3.0 kg fibers/m3 concrete. Within this research project, the theoretical basis for transport processes and chemical reactions shall be developed and applied to different types of lining concrete. Starting with the identification of material properties such as the permeability of concrete at different temperatures, a multiscale model for the estimation of the advection properties shall be developed. For the verification of the employed multiscale approach, experiments at the considered scales of observation are performed. These experiments such as differential thermal analysis, thermo gravimetry, mercury porosimeter and macroscopic permeability tests will be conducted at the laboratories of the Institute for Mechanics of Materials and Structures and the Institute for Building Materials, Building Physics, and Fire Safety.

People

Project leader

Project personnel

Institute

Grant funds

  • FWF - Österr. Wissenschaftsfonds (National) Austrian Science Fund (FWF)

Research focus

  • Composite Materials: 30%
  • Computational Materials Science: 30%
  • Computational System Design: 5%
  • Surfaces and Interfaces: 15%
  • Modeling and Simulation: 20%

Keywords

GermanEnglish
TunnelTunnel
Tunnelschalelining
Feuerfire
Permeabilitätpermeability
Mikromechanikmicromechanics

External partner

  • Institut für Hochbau und Technologie

Publications