Determination of impregnation of polystyrene foam boards

Abstract

Article gives analysis of experimental results of water absorption by expanded polystyrene slabs. The investigation was carried out applying different test methods. It was established that the most precise results of water absorption by expanded polystyrene are obtained when method of increased pressure is applied. Results obtained applying this method show that the water absorption of expanded polystyrene considerably increases when its density decreases. When the specimen is immersed, the largest amount of water is accumulated between the pores. Due to an even pressure distribution around the walls of the specimen, water does not push out the air, which is between the pores, and, therefore, a part of the specimen does not soak through. Moreover, spaces between expanded polystyrene pores usually interact, and, depending on the density of a product, the diameter of them may be up to few millimetres. When the specimen is withdrawn from water, all of a sudden the greatest amount of water retires from the spaces between the pores.

Statybinių medžiagų įmirkis nustatomas keliais būdais: paprastai mirkant, virinant vandenyje, didinant vandens slėgį, vakuumuojant. Tačiau ne visi bandymų metodai tinkami skirtingoms statybinėms medžiagoms. Sertifikuojant polistireninio putplasčio gaminius, įmirkis nustatomas pagal EN 12087 standarto reikalavimus, kai bandinys visiškai panardintas išlaikomas 28 paras. Polistireninio putplasčio poros yra uždaros ir į jas negali prasiskverbti vanduo. Pagrindinė vandens masė, panardinus bandinį, susikaupia polistireninio putplasčio plokščių tarpuporiuose. Dėl nedidelių slėgio skirtumų aplink bandinio sieneles tarpuporiuose esančio oro vanduo neišstumia ir dalis bandinio neįmirksta. Be to, polistireninio putplasčio tarpuporiai dažniausiai yra susisiekiantys tarpusavyje ir priklausomai nuo gaminio tankio gali būti iki keleto milimetrų skersmens. Bandinį išėmus iš vandens, didžioji vandens dalis staiga pasišalina iš tarpuporių.