Effective permittivity modelling of lime-cement perlite plaster

The effective permittivity (epsilon(eff)) of lime-cement perlite plaster has been theoretically modelled on the basis of fractal pore-size distribution (FPD) function of the corresponding solid-air-water (S-A-W) heterogeneous material. The method of Friedman [1] has been applied in FPD related calculations of the epsilon(eff) of AWS, SWA three-phase composite spheres and of a water content/porosity ratio weighted sum of SWA and ASW composite spheres, corresponding to the assumed, dielectric signal dominating heterogeneous structures. Good correspondence has been obtained between the theoretical dependence of epsilon(eff) on the volumetric water content - in the case of model, based on SWA composite spheres - and the experimental one, measured for the lime-cement perlite plaster probe [2] using time domain reflectometry (TDR) technique.