Creep of Hardened Portland Cement Paste Under Cyclic Temperature

Autor: E. C. Rainford, J. Timusk
Rok vydání: 1978
Předmět:
Zdroj: Journal of the American Ceramic Society. 61:380-385
ISSN: 1551-2916
0002-7820
DOI: 10.1111/j.1151-2916.1978.tb09341.x
Popis: Sealed cement paste specimens (water/cement ratio 0.5), loaded at 28 days to a constant stress/strength ratio of 0.2, were subjected to cyclic temperatures of 90° to 23°F (32.2° to —5°C) and their creep behavior was studied in relation to the amplitude, frequency, and mean value of the cyclic temperature. Temperature cycling increased creep above that which occurred at the mean temperature and this creep may be greater than that which would occur at the highest temperature. Assuming that creep is a rate-process phenomenon, it is possible to predict the creep under one temperature regime, given the creep under another and the temperature histories of both. Also, the ratio (creep under cyclic temperature/creep at the mean constant temperature) bears a hyperbolic cosine relation to the temperature amplitude; thus, if all else is equal, a greater amplitude gives a greater creep. Within the limits of the experiment, the greater the period of the cyclic temperature the greater the creep. The increase in creep above that at mean temperature appears to be greater when the mean temperature is in the range where evaporable water freezes. Irrecoverable creep appears to increase with the amplitude of temperature as well as with temperature per se. The influence of variable temperature on creep is explained in terms of the superimposition of hygrothermal diffusion on stress-induced moisture diffusion in the creeping specimen, as well as the influence of temperature on the diffusion coefficient of the diffusing mass.
Databáze: OpenAIRE
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