Numerical simulation of the cone calorimetric tests on concrete samples with and without polypropylene fibres

Reinforced concrete structures have adapted new types of concrete (high strength, self-compacting, etc.) presenting different thermo-mechanical behaviour, acquiring special importance the analysis of spalling. One of the most common procedures to minimize this failure event is the addition of polypropylene fibres to natural components. The experimental study of concrete under fire conditions in general, and the development of new numerical models in particular, has allowed the assessment of complex phenomena to determine the thermal performance. This investigation studies the thermal performance of a two dimensional model, using nonlinear and transient finite element analysis. The experimental analysis is based on calorimetric test, using small-scale samples of concrete. The numerical simulation model was defined to evaluate the thermal performance of samples when submitted to different heat fluxes 35 and 75 kW/m2 and different levels of fibres contents (0, 600 and 1200 g/m3). In order to validate the numerical model, small changes to standard test procedure were made. The numerical model does not predict the motion of the moisture in the samples, but nevertheless is able to predict the thermal performance. It can also be concluded that addition of different amounts of polypropylene fibres has no significant effect on the heat release rate and on the thermal performance of the samples.

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