Thermal characteristics of the external walling made of cold-formed steel studs and polystyrene concrete

Abstract

The paper proposes to use polystyrene concrete as an insulating material in wall panels made of light gauge studs. It should solve the problem of thermal bridges in such panels. The strength and the heat conductivity factor for polystyrene concrete with the density of 300-1300 kg/m3 were determined. Results showed that by increasing the density of polystyrene concrete by 4.1 times the thermal conductivity is increased by 3.7 times, which is an almost linear relationship. For instance, the strength at a density of 300 kg/m3 is 0.25 MPa, while at a density of 1300 kg/m3 it is already 8.2 MPa, which is 30 times more. For samples of different density, a scattering of deformations under compression was recorded. A full deformability of PSC cubes of 1292 kg/m3 density was on average 1 mm, while for 309 kg/m3 cubes it was 10 mm, indicating a larger deformability of low-density polystyrene concrete. The experimental samples of wall panels were assembled and their heat-transfer resistance was measured in the laboratory. It was found that the presence of thermally conductive inclusions in the wall structure reduces heat resistance up to 50 %. It was proposed to use profiled sheeting as an external wall covering. Besides, it is necessary to design the wall so that the external flange of the sheeting is placed across the heat-conducting inclusions. The gap between the profile and the sheeting is filled with polystyrene concrete and serves as thermal pad. This method of increasing energy efficiency of cold-formed steel and polystyrene concrete wall structures is purely structural and does not require additional costs. By increasing the web height of the profiled sheeting, the effect of heat conducting inclusions is reduced in direct proportion – by 40% at 20 mm, by 20% at 40 mm and by 10% at 50 mm. The proposed method is theoretically and experimentally proven.