Water absorption of expanded polystyrene boards

The water absorption of expanded polystyrene boards was studied with the aim of developing a procedure for prediction of long-term absorption on the basis of short-term absorption data. The specifications of EN 12087 on test methods for determining long-term water absorption of expanded polystyrene by total immersion over a period of 28 days have been discussed and some disagreement between the specifications provided by EN 12087 and EN 13163 have been observed. The results obtained in determining water absorption of specimens of EPS boards with density ranging from 12 to 35 kg/m(3), which were manufactured by various firms by foaming raw beads supplied by various manufacturers, are presented. The tests were performed in accordance with methods 2A and 2B (EN 12087). Based on regression equations presented in the paper, a comparison of the experimental results obtained after different periods of immersion was made. Interval prediction (for 15 yr) of the increase of long-term water absorption for EPS boards is described. A special coefficient K is used to correct for the expansion of the boundaries of confidence interval due to discounting of experimental information. (C) 2006 Elsevier Ltd. All rights reserved.