Journal Published Online: 16 March 2021
Volume 49, Issue 6

Effects of Atmospheric Pressure on Water Absorption in Plastic Insulation – A Laboratory Investigation

CODEN: JTEVAB

Abstract

Plastic insulation materials, particularly polystyrene insulation, are widely used in the construction sector because of their good insulating capabilities and mechanical stability. However, in many building applications, the insulation materials are exposed to high levels of moisture over prolonged periods, which increases the thermal conductivity of the material and may facilitate growth of fungi. In order to minimize the extent and impact of moisture absorption in plastic insulation, more knowledge is sought on the exact process by which water is absorbed. In this article, tests of water absorption by complete immersion are carried out on expanded polystyrene (EPS) and extruded polystyrene (XPS), following Method 2A of the European Standard EN 12087:2013, Thermal Insulating Products for Building Applications - Determination of Long Term Water Absorption by Immersion, but over a longer duration (227 days) and with more frequent measurements than mandated by the standard. Over 91 days, EPS was found to absorb an amount of water approximately four times its dry mass. Observations indicate that the water absorption of EPS is significantly influenced by fluctuations in atmospheric pressure. A drop in pressure of 50 hPa between two measurements 1 week apart led to a 15 wt.% decrease in the water content of submerged EPS samples. XPS was found to absorb significantly less moisture than EPS, with a weight increase less than 15% over 91 days and with negligible influence from variations in atmospheric pressure. The impact of atmospheric pressure fluctuation is currently not accounted for in any testing standards. As such, this article uncovers a major source of uncertainty in the testing procedure of EN 12087:2013 and its ASTM counterparts.

Author Information

Andenæs, Erlend
Department of Civil and Environmental Engineering, Norwegian University of Science and Technology, Trondheim, Norway
Stagrum, Anna E.
Department of Civil and Environmental Engineering, Norwegian University of Science and Technology, Trondheim, Norway
Kvande, Tore
Department of Civil and Environmental Engineering, Norwegian University of Science and Technology, Trondheim, Norway
Lohne, Jardar
Department of Civil and Environmental Engineering, Norwegian University of Science and Technology, Trondheim, Norway
Pages: 14
Price: $25.00
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Stock #: JTE20200337
ISSN: 0090-3973
DOI: 10.1520/JTE20200337