Prediction and Control of Cracking in Reinforced Concrete Structures

Cracking is a very important factor in predicting the behavior of RC structures both in terms of their load bearing capacity, as well as various serviceability criteria. For example buried concrete containment structure for low-level nuclear waste may be controlled by the loss of its load-bearing capacity or an increase in permeability. The latter factor is controlled by the general degradation of the concrete and by the presence of discrete cracks resulting from externally applied loads or from restraint to normal volume changes. To be able to predict the effects of cracks on permeability, it is necessary to understand the causes and mechanisms of discrete crack formation in reinforced concrete structures. The objective of this paper is to provide an overview of the behavior of reinforced concrete members and to discuss the factors affecting the formation of cracks in hardened concrete. Models for predicting the width of flexural cracks are reviewed. Factors affecting drying shrinkage cracks and approximate methods for considering them are discussed. An example is provided to illustrate how to determine whether drying shrinkage cracks will develop under specific conditions. This is followed by a discussion of techniques to predict the number and widths of drying shrinkage cracks. Finally, there is a discussion of the interaction between flexural and drying shrinkage cracking. The paper contains variety of technical information, gathered from several sources, which can be useful for readers who want to know more about the structural aspects of reinforced concrete.

Keywords:

reinforced concrete , cracking , creep , restrained shrinkage