This paper summarizes most of the aspects and details related to testing for creep and shrinkage in concrete. The experimental determination of con-crete creep and shrinkage is discussed in detail, analyzing each of the condi-tions likely to be encountered during planning, testing and reporting test data. The subjects discussed are: objectives of test programs, test concept, as-sumptions, designing a test program, standard test methods for creep and shrinkage, test specimens, equipment for measuring deformations, concrete-mixing, batching and preparation of test specimens, testing environments, tem-perature and humidity tolerances, deformation measurement schedule, docu-mentation and interpretation of test results. Test programs are presented in detail. Field studies are discussed and correlated to laboratory test programs for three types structures sensitive in varying degrees to effects of creep and shrinkage. That is, field studies of reinforced and prestressed concrete nuclear containments, the uneven long-term shortening of columns with respect to the shear walls in reinforced concrete high rise buildings with shear walls, and the determination of prestressing forces, cambers, deflections and prestress loss in prestressed members.

The effect of ambient temperature and humidity to which concrete is exposed prior to or during loading should be taken into account; when creep and shrinkage are predicted. The purpose of this study is to clarify the effect of ambient temperature and humidity on the creep and shrinkage of concrete. In this study, we carried out creep and shrinkage tests under constant and varying histories of temperature and humidity. Creep and shrinkage tests sub-jected to ambient temperature and humidity were also carried out in the room where the effect of rain and wind were negligible. The effect of temperature on shrinkage is much bigger than that of changes in humidity. The shrinkage strain on concrete subjected to increase in temperature is much bigger than that measured under constant temperature. The magnitude of creep and shrinkage is highly influenced by the difference of the season in which concrete is cast. The effect or variance of humidity on creep seems to be small. The temperature of curing water before application of load significantly influenced creep of concrete.

A simple model for the characterization of concrete creep and shrinkage in design of concrete structures is proposed. It represents a shortened form of model B3 which was presented in [2] (as and improvement of the original version [3]) and appears in this volume, and an update of a previous short form [4]. The main simplification compared to model B3 comes from the use of the log-double-power law as the basic creep compliance function. The B3 formulae for predicting material parameters in the model are simplified by dropping the dependence of these parameters on the composition of concrete mix, leaving only dependence on the strength and the specific water content of the concrete mix. The model is justified by statistical comparisons with all the data in the internationally accepted RILEM data bank. The differences be-tween the present short-form and model B3 are discussed and limitations of the short form are compared to model B3 are noted. The model is suitable for design of concrete structures with the exception of highly creep-sensitive struc-tures for which the full model B3 is necessary

This paper presents a simple design-office procedure for calculating the shrinkage and creep of concrete using the information available at design; namely the 28 day specified concrete strength, the concrete strength at end of curing or loading, element size and the relative humidity. The method includes strength development with age, relationship between modulus of elasticity and strength, and equations for predicting shrinkage and creep. The only arbitrary information are the factors appropriate to the cementitious material, which can be improved from measured strength age data. At the most basic level the proposed method requires only the information available to the design engi-neer. The prediction values can be improved by simply measuring concrete strength development with time and modulus of elasticity. Aggregate stiffness can be taken into account by back calculating a concrete pseudo strength from the measured modulus of elasticity. Measured short term shrinkage and creep values can be extrapolated to obtain long duration predictions for simi-lar sized elements. The predictions are compared with experimental results for seventy nine data sets for compliance and sixty three data sets for shrink-age. The comparisons indicate shrinkage and creep can be calculated within +/- 25%. The method can be used regardless of what chemical admixtures or mineral by-products are in the concrete, casting temperature or curing regime.

This Symposium Publication contains 12 papers presented at the Adam Neville Symposium in Atlanta, Georgia, in 1997. Topics relating to creep and shrinkage include admixture and cementitious materials effects, special high-performance considerations, temperature and humidity influences, reinforced and prestressed concrete analysis and design procedures, and much more. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP194