ACI 209.1R-05 Report on Factors Affecting Shrinkage and Creep of Hardened Concrete.
Chapter 3—Factors affecting creep, p. 209.1R-8 3.1—Introduction 3.2—Effect of mixture proportions on creep 3.3—Effect of environment on creep 3.4—Effect of construction and structural design on creep Chapter 4—References, p. 209.1R-11 4.1—Referenced standards and reports 4.2—Cited references and reports CHAPTER 1—INTRODUCTION 1.1—Scope Factors affecting shrinkage and creep of hardened concrete are presented to enable those involved in the evaluation and formulation of concrete mixtures to determine the effects of these factors. Section 1.2 of Chapter 1 defines terms used by those evaluating shrinkage and creep, while Chapters 2 and 3 describe effects of various factors on shrinkage and creep. This document does not include information on the prediction of shrinkage and creep or structural design issues associated with shrinkage and creep.
1.2.1 Total strain —Total strain is the total change in length per unit length measured on a concrete specimen subjected to a sustained constant load at uniform tempera- ture. As shown in Fig. 1.1, total strain is the sum of shrinkage and load-induced strain. 1.2.2 Shrinkage—Shrinkage is the strain measured on a load-free concrete specimen. Shrinkage does not include changes in length due to temperature variations, but depends on the environment and on the configuration and size of the specimen. Shrinkage strain is usually measured by casting companion load-free specimens identical to the loaded concrete specimens used to measure the total strain. These companion specimens are cast from the same concrete batch, have the same dimensions, and are stored in the same environment as the loaded concrete specimens. Shrinkage values are given as dimensionless strains (length change over a given length) expressed as percent, mm/mm, or in./in. It is common to describe shrinkage in microstrain or millionths, as the value of strain × 10 6 . Thus, 1000 microstrain is equivalent to 1 × 10 –3 mm/mm. Values of long-term concrete shrinkage are typically between 200 and 800 × 10 –6 mm/mm, (200 to 800 microstrain) (Zia, Ahmad, and Leming 1997) and mortar shrinkage typically between 800 and 2000 × 10 –6 mm/mm (800 and 2000 microstrain) (Heath and Roesler 1999). ACI 209.1R pdf download.