Towards prediction of the thermal spalling risk through a multi-phase porous media model of concrete

Physical phenomena in heated concrete, leading to thermal spalling are discussed. Contribution of the stored elastic energy and vapour pressure build-up to the kinetic energy of spalled concrete pieces is estimated. A mathematical model of hygro-thermo-chemo-mechanical phenomena in heated concrete is presented. Different simplified models of thermal spalling are used to define special indexes, aiming for quantitative assessment of its risk. These are tested for the results of numerical simulations based on an experimental test. A simplified energy analysis to estimate the kinetic energy of spalled concrete pieces and to make predictions about explosive or non-violent character of the phenomenon is proposed.