Title: Shrinkage and Creep of High Strength Concrete

Author(s): Ali S. Ngab, Arthur H. Nilson, and Floyd O. Slate

Publication: Journal Proceedings

Volume: 78

Issue: 4

Appears on pages(s): 255-261

Keywords: autogenous healing; compressive strength; creep properties; deformation; drying shrinkage; high strength concretes; loads (forces); shrinkage; specimens; strains; stresses.

DOI: 10.14359/6922

Date: 7/1/1981

Abstract:
Results of an experimental program on the time-dependent deformation and sustained load strength of high strength concrete are presented. Comparison with normal strength concrete under similar conditions indicates significant differences which should be accounted for in design. Sealed and unsealed specimens were subjected to uniaxial compressive stress for load periods up to 90 days. The main variables investigated included concrete strength, conditions of drying, age at first loading, intensity of load, and duration of load. It was found that creep may be much less for high strength concrete than for normal strength material, especially when specimens are permitted to dry under sustained load, as would normally be the case in structures. Shrinkage appears to be somewhat greater than for normal strength concrete. The effect of sustained compressive stress up to about one-half the short-term strength is to increase the compressive strength of both high strength and normal strength concrete. Higher sustained stress has a detrimental effect on the strength of both. Regardless of stress intensity, the ratio of sustained load strength to short-term strength is higher for high strength than for normal strength material. All behavior was correlated with progressive in ternal microcracking. Microcracking studies are reported in a separate paper.