Creep and shrinkage of concrete

The paper gives a short description of the different types of test series on creep and shrinkage of concrete, which are under work at the Cement and Concrete Research Institute at the Technical University of Norway. Some results are given concerning creep and shrinkage of concrete under periodic changes in moisture content. It is found that a very short time of immersion in water— 6 hours weekly— will reduce the creep permanently. This holds also if the concrete later on is exposed to rather hard drying conditions. A study of concrete under periodically varying stresses showed that a characteristic stress, σB, applied as a constant stress equalized the periodically varying stresses within reasonable limits for the creep development. A rough estimation for the characteristic stress is given. Creep under decreasing and under increasing stresses as well as creep and shrinkage of concrete with low prehardening values are studied in special test series.