Influence of the moisture in the thermal conductivity of Expanded Polystyrene insulators

This paper presents measurement results of the thermal conductivities of different expanded polystyrene (EPS) insulation materials before and after wetting. The measurements were achieved on three different pure (white) EPS and on the graphite - enhanced (grey) EPS samples with 0.3 x 0.3 x 0.05 m geometries, carried out by a Holometrix type 2000 series heat flow meter. The measurements were performed after desiccating the samples in a Venticell 111 type drying apparatus to changeless weight at 343 K, and after treating them in a Climacell 111 climatic chamber at 293 K and 90 % relative humidity for 16 to 24 hours. The change in the lambda value in function of wetting time as well as in function of moisture contents will be presented. Refined constants for the equations of the change in thermal conductivity in function of moisture content for EPS materials will be reported as well. The research of Akos Lakatos was realized in the frames of TAMOP 4.2.4. A/2-11-1-2012-0001, National Excellence Program - Elaborating and operating an inland student and researcher personal support system convergence program". The project was subsidized by the European Union and co-financed by the European Social Fund."