Freezing-Thawing Processes in Building Walls

主要研究结果如下：1.与NRC（加拿大国家研究理事会）合作，进行了冻融实验，其中玻璃纤维样品被用作典型的绝缘材料。通过使用伽马射线装置，在不破坏样品的情况下连续测量测试样品中的水分（冰和水）含量。从而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。考虑了二维的水分和温度分布，对冻结过程进行了模拟，得到了令人满意的结果.对ALC墙体冻融过程的分析与试验结果吻合较好，试验中试件是在积冰应力作用下破坏的.对京都市建筑物的冻害情况，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，研究了降雨和夜间辐射等外部条件对冻融过程的影响。它被证明是重要的。

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.