Evaluation of creep of high-strength concrete at early ages

The creep characteristics of the high-strength concrete drastically change during the early ages, particularly from 1 or 2 days after mixing. This paper presents discusses results of creep measurements made after a period of 20 days from the application of the load. For instance, the creep when loading started at the ages of 2,3, and 14 days were, respectively, https://www.w3.org/1998/Math/MathML" display="inline"> 75 % , https://www.w3.org/1998/Math/MathML" display="inline"> 70 % , and https://www.w3.org/1998/Math/MathML" display="inline"> 43 % of the value of the case in which loading started at the age of 1 day. A satisfactory way of defining the basic creep functions was devised in terms of the product of a coefficient for the ultimate creep and a coefficient for the rate of creep progress. In addition, the creep under variable stress, which involves stress reversal, was estimated by the method of superposition. The estimated creep values generally show good agreement with the measured values, though immediately after the stress reversal they tend to be slightly higher.