気温変動とコンクリート構造物の収縮ひびわれとの関係 : その 2 : 気温変動に対応するコンクリートの引張 (曲げ引張) クリープについて

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In Part 1, atmospheric temperature variation as a cause of concrete cracking was reported. In this paper reported are the test results of creep of concrete in flexure subjected to increasing stresses in short-term (12 hours) loading corresponding to the short-term variation of atmospheric temperature. For the experimental study of the creep, prisms of 10×10×40cm were used. They were made of ordinary Portland cement, river sand and river gravel with three water/cement ratios of 0.45, 0.55 and 0.65 respectively. A part of the specimens was cured under water at the temperature of 20 degree centigrade until the test age of 3, 7, 28, 91 and 180 days. The rest was stored in the dry air at the temperature of 20 degree centigrade and 50% R. H. until the test age of 28, 91 and 180 days. The specimens were subjected to increasing stresses by stepped method with maximum stress-strength ratio 0.8. The results obtained are as follows : The creep coefficient of the specimens cured under water at the temperature of 20℃ until 28〜180 days were 0.4〜0.6, and that cured at 20℃, 50% R. H. until 28〜180 days were 0.1〜0.3. The creep coefficients mentioned above were much smaller than that obtained from the specimens subjected to a constant stress for a long time.
社団法人日本建築学会の論文
1975-11-30