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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

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.

Creep and shrinkage of concrete are important factors in the design and analysis of concrete structures, particularly for the long-term serviceability and durability and for the construction stage of long span, prestressed con-crete structures. Because of very low water-cementitious ratio (w/cm), chemical admixtures and sometimes mineral admixtures, the evolutions of moisture state and rate of cement hydration in high-performance concrete (HPC) are significantly different from those in normal concrete. For example, the cement hydration in HPC terminates earlier due to the lack of water, resulti ng in faster development of relative strength at early ages and little long-term strength gain. At the same time, self-desiccation in the form of a rapid decrease in internal relative humidity starts in HPC at very early ages. Consequently, base (autogenous) shrinkage of HPC is very high compared with normal concrete. The moisture permeability, which affects the development of creep and shrinkage of concrete, is at least one order smaller for HPC than for normal concrete. As a result well as creep and the development shrinkage property of strength and modulus of elasticity as es of HPC are remarkably different from those of normal concrete. The current prediction models for time-dependent properties, particularly creep and shrinkage, which have been derived from experimental data on normal concrete, are not applicable to HPC. This paper will discuss the main parameters affecting the time-dependent properties and the differences between HPC and normal concrete, based on the results of an extensive experimental program at the University of Calgary and data from the literature. A recently developed model to estimate creep and shrinkage of HPC is also presented and examined.

This review assesses the general effects on elasticity; creep and shrinkage of concrete arising from the use of admixtures: plasticizers (water-reducers), super-plasticizers (high range water-reducers), slag, fly ash and silica fume. Previously published test data are collectively analyzed to quantify creep and shrinkage of concrete containing the admixture as a proportion of creep and shrinkage of plain concrete having the same mix proportions. The analysis shows the effects of the admixtures are highly variable and the expressions given for predicting deformations are only recommended in the absence of test data.

This paper presents a comparison between laboratory creep and shririkage data and the performance of a long-span box-girder bridge structure. As part of a long-term instrumentation and monitoring program on the North Halawa Valley Viaduct, a number of laboratory creep and shrinkage tests were performed on the concrete used in the viaduct. The data are compared with current theoretical models for the prediction of creep and shrinkage. These models all underestimate the long-term effects on the concrete used in this structure. This is attributed in part to the nature of the basalt aggregates available on the Hawaiian Islands. It is shown that with as little as 28 days of data from creep and shrinkage tests, the prediction models can be modified to provide a far more accurate prediction of the long-term performance of the structure.