Numerical simulation of polypropylene fibres in concrete materials under fire conditions

• The role of PP fibres on concrete at high temperature is numerically evaluated.
• Porosity variations in concrete at elevated temperatures are accounted for.
• An addictive decomposition for porosity is presented.
• An appropriate hygro-thermal FE code is developed to such a scope.

In recent years experimental investigations have demonstrated that the risk of spalling for a concrete material under fire conditions is drastically reduced by using a low dosage of polypropylene fibres in the mix design. This effect can be explained by considering the increase in voids connectivity within the cement paste and in concrete porosity due to polypropylene evaporation above certain temperatures.In this work the complex mechanism of polypropylene contribution on concrete behaviour under thermal conditions has been numerically evaluated through a coupled hygro-thermal–mechanical finite element formulation.