Modeling concrete exposed to high temperature: Impact of dehydration and retention curves on moisture migration

High-performance concrete is a widely used building material for tunnels, high-rise buildings, nuclear plants etc. When these structures are exposed to fire, high-performance concrete is prone to spalling. Moisture migration is believed to be one of the processes directly related to this phenomenon. In this paper, moisture profiles measured experimentally from neutron radiography on heated concrete are compared with results from a numerical model implemented in the finite element code Cast3M. The water loss measured experimentally, and the numerical results suggest that the commonly used constitutive laws for dehydration and water retention curves need to be reconsidered. The influence of these constitutive laws on the moisture migration is investigated. The dehydration constitutive law plays an important role on the dehydration front but has negligible effect on the moisture accumulation behind this front. By contrast, the water retention curves do not influence the dehydration front but affect the quantity and location of water condensation. The role of the permeability is also discussed.