結露水の凍結融解回数マップの提案 : 高分子系建築材料の耐久性に関する研究(その4)

抄録

There are many degradation agents for polymeric building materials. The effect of cyclic freezing and thawing is very severe for extrior finishing materials perticularly. Dewing penomena occurs on the surface of materials when relative humidity is higher than 80 %, according to the criterion of ISO/TC 156/WG 4. Dew drops freeze and melt when temperature fructuates across the freezing point. According to the ambient temperature, the number of freezing and thawing cycles is estimated at 154 points in Japan. Materials used outdoors are heated by solar radiation in daytime and cooled down by extraterestrial radiation at clear night. It is reasonable to count freezing and thawing cycle based on the temperature of black panel, which is similar to the real building materials. Then, authors quantified the number of freezing and thawing cycle provided by the daily maximum and minimum temperatures of opened/insulated black panel calculated from climatic factors at different 66 parts in Japan. The frequency of freezing and thawing cycles based on the black panel temperature is 4-5 times, or 7-8 times in Hokkaido, as much as the number of freezing and thawing cycles related to the ambient temnerature Obtained results are plotted on maps.