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Study on Influence of Heat and Humidity on The Adhesive Performance of Base Mortar of External Wall.

热、湿对外墙基层砂浆粘结性能影响的研究。

基本信息

批准号：
04452248
负责人：
NAGAMATSU Seiki
金额：
$ 2.69万
依托单位：
OITA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

In the sequence from last year, the experiments have been carried out on the concrete walls finished by mortar. Some of them have been heated upto 80ﾟC at the face by infrared lamps and cooled down to circumstane temperature (or+humidity) and others exposed out door.The contact planes with mortar and concrete wall have been in two conditions, "normal" and "having partially pre-cracking" (Ref.fig-1, Type1).In this year, additional experiments have been done. The specimens with pre-crackings (Type1,2) have been heated up as same as above and the behavior of pre-cracking have been inspected.The exprimental results have been as follows ;(1) The adhesive strength with mortar and concrete wall has been lowered 40% after a month in the case of only heating up.(2) The drop in adhesive strength of "normal" was amaller in the case of (heating+giving humidity) than in the case of only heating. On the other hand, the drop in the adhesive of "pre-cracking Type-1" was much larger in the case of (heating+giving humidity) than in the case of only heating.(3) The adhesive strength of "normal" have been lowered 7% after 90 days from exprimental start and that of "pre-cracking Type-1" have been lowred 37%.(4) The cracking in mortar have been observed in all the specimens, especially the specimens with "pre-cracking Type-1" have had wider cracking.(5) At the roots of "pre-cracking Type-1,2", the extention of that have ben observed. These are a mechanical reason of mortar pealing off concrete wall.2) The temperrature distributions in the specimen which have been heated up infrared lamps have been analyzed by F.E.M.. The calculated results have agreed with the mesured temperature.3) The calculation of stress distribution in the specimen have been carried out based on the temperature distribution calculated in item 2). They are shown that the enough magnitude of tensile stress for cracking to occur exists in mortar.

在去年开始的序列中，实验是在用砂浆完成的混凝土墙上进行的。其中一些已经被红外线灯加热到面部80ﾟC，冷却到环境温度(或+湿度)，另一些暴露在室外。与砂浆和混凝土墙接触的平面处于两种状态，“正常”和“部分预裂”(参考文献1，类型1)。今年，又做了一些实验。对有预裂(1，2)的试件进行了同样的加热，并对预裂行为进行了考察。试验结果如下：(1)在只加热的情况下，砂浆与混凝土墙体的粘结强度在一个月后下降了40%。(2)在(加热+给湿)的情况下，“正常”的粘结强度的下降幅度比只加热的情况下的要大。(3)“正常”胶粘剂的粘结强度在试验开始90天后下降了7%，“预裂1号”胶粘剂的粘结强度降低了37%。(4)所有试件都出现了砂浆开裂现象，特别是“预裂1号”胶粘剂的开裂范围更广。(5)在“预裂1，2”胶粘剂的根部，本观察到的扩展范围更大。这些都是砂浆剥落混凝土墙体的力学原因。2)用有限元分析了红外灯加热后试件内的温度分布。3)根据第2项计算得到的温度分布，对试件内部的应力分布进行了计算。它们表明，砂浆中存在足够大小的拉应力来产生裂缝。