Transport and Reaction Processes in Concrete at High Temperatures

Simulating processes in concrete at high temperatures requires coupled formulation of transport and reaction. Transport can be formulated using balance equations for mass and heat as well as constitutive equations. The equations have to be valid in the whole temperature range from 293 K up to 1000 K. Instantaneous thermodynamic equilibrium is assumed for the gas and liquid phase of water substance. Above the critical point of water, only its gas phase exist. This requires a combined mass balance, which contains vapour balance as well as the mass balance of liquid water. Rapid evaporation of water and degradation of cement minerals leads to an enormous pressure increase in the gas phase. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)