Water absorption of several different frost insulation materials was tested for four years.
The test took into account both immersion and frost attack to materials. On the basis of the
research the water absorption on XPS specimens is significantly minor compared to EPS
specimens that were studied. The most significant result was that freezing of test
specimens did not affect on water absorption of XPS specimens but had a major effect on
water absorption of EPS specimens. With frozen EPS specimen the absorption continued
increasing even after 48 months of immersion. Presumably the reason for such a behaviour
is that the pore structure of EPS is not able to resist the tension caused by freezing water
and therefore cracks are formed. Thus, more water absorbs inside the EPS through the
cracks and it causes cracking deeper in the specimen which is why absorption increases
after every freezing period.