Climate Change Effect on Freeze-thaw Load in Finland

Freeze-thaw damage is one of the major degradation mechanisms of climate exposed porous rock-based building materials in existing Finnish building stock. In recent studies, it has been shown that not only the amount of freeze-thaw cycles but especially the amount of wind-driven rain (WDR) before freeze-thaw cycles has a major effect on the rate of freeze-thaw damage in concrete structures. In this study, freeze-thaw cycles after a rain event, the average annual amount of WDR before freeze-thaw cycles and the average amount of WDR before each cycle is calculated in different locations in Finland. The calculations are made for present and projected 2050 and 2080 climates with three greenhouse gas scenarios: RCP2.6, RCP4,5 and RCP8.5. Based on the results, the freeze-thaw load is decreasing in coastal and southern areas and staying at current level or increasing in northern parts of Finland. In addition, the level of freeze-thaw load is getting less direction or geographically dependent. The results strongly indicate that the exposure level might be decreasing in coastal area and southern parts of Finland because both the freeze-thaw cycles and the annual amount of WDR before cycles are decreasing. However, an average amount of WDR before a freeze-thaw cycle is actually increasing and so, the intensity of freeze-thaw attack is not decreasing. Thus, for the future climates freeze-thaw durability of porous rock-based structures should be still emphasised.