Freezing-Thawing Processes in Building Walls

所获得的结果概括如下：1.在与加拿大国家研究委员会(NRC)的合作下，进行了一项冻融实验，其中玻璃纤维样品被用作典型的绝缘材料。利用伽玛射线仪，在不破坏样品的情况下，连续测量样品中的水分(冰和水)含量。从而可以得到含水率分布的时间历程。基于热质同时传递理论，分析了玻璃纤维墙体在恒定外界温度下的冻融过程。通过考虑水分和温度分布的二维分布，得到了关于冻结过程的令人满意的结果。对混凝土墙体内冻融过程的分析与试验结果吻合较好，试验试件被积冰应力破坏。对京都市区建筑物的冻害，特别是墙体裂缝进行了调查。发现了许多病例。在日本相对温暖的地区，研究了降雨、夜间辐射等外界条件对冻融过程的影响。事实证明，这一点意义重大。

The results obtained are summarized as follows.1. In collaboration with NRC (National Research Council, Canada), a freezing-thawing experiment was carried out where a glass-fiber sample was used as a typical insulation material. By making use of Gamma ray apparatus, the moisture (ice and water) content in the test sample was continuously measured without destroying the sample. Thus, the time history of the moisture content distribution could be obtained.2. The freezing-thawing processes in the glass-fiber wall under constant external temperatures were analyzed based on the theory of simultaneous transfer of heat and mass. By taking into account the two-dimensional distribution of the moisture and temperature distributions, a satisfactory result was obtained regarding the freezing process.3. An analysis on freezing-thawing processes in the ALC wall agreed reasonably well with the experimental results where the test sample were destroyed by the stress caused by ice accumulation.4. A survey of the frost damage, especially cracks of the building wall, was carried out in Kyoto city. Many cases were found.5. The influence that the external conditions such as rain and nocturnal radiation have on freezing-thawing processes was investigated in the relatively warm area in Japan. It was shown to be significant.