COUPLED HEAT AND MASS-TRANSFER IN CONCRETE ELEMENTS AT ELEVATED-TEMPERATURES

Realistic simulation of the coupled heat and mass transfer in concrete elements requires detailed knowledge of the dominant transfer mechani sms. Transfer under thermal gradients implies that several transport m echanisms, such as diffusion and Darcy flow, may be simultaneously con tributing to hygral transfer, depending on the local temperature and m oisture content. The relevant transport processes can be described as functions of thermodynamical state variables, and incorporated into a numerical model for simulation of coupled heat and mass transfer. A se t of transport coefficients has been determined, as well as experiment al moisture distributions in a prestressed concrete vessel under therm al gradients. These measurements are compared with the results of a nu merical simulation based on a description of physical transfer process es relevant to porous media.