Impact of perlite, vermiculite and cement on the thermal conductivity of a plaster composite material: Experimental and numerical approaches

International audienceThis work is dealing with the thermo mechanical behaviour of a new composite material used as thermal insulator and for fire passive protection in building construction. The composite panel results of combination of a calcium sulphate hydrates matrix mainly water and inorganic mineral additives. The effective thermal conductivity of the composite is measured by the hot-disc method. Analytical and numerical models are used to determine the composite thermal conductivity which can be expected vs the rate of additives. The experimental values are compared with analytical and numerical models. In particular, effective medium percolation theory (EMPT) for a two-phase system gives analytical values which are close to the experimental results. Moreover, the numerical model based on a simple description can allow the description of the thermal conductivity evolution with the rate of additives. An unexpected phenomenon which can be attributed to the confined water in additives can explain the gap between the numerical models and the experimental results