ABSTRACT
Shrinkage of repair material is the major factor inducing cracking in concrete repairs. It has been reported that the repair mortars are restrained against shrinkage by the substrate concrete and steel reinforcement within the repair patch [Yuan, and Marosszeky, 1991]. Induced cracks in repair materials are due to restrained shrinkage. The amount of shrinkage depends on many factors including the cement content, aggregate properties, the mixture composition, temperature and the relative humidity of the environment, the age of the concrete and the size of the structure. The ring test is commonly used to assess the potential for restrained shrinkage induced cracking due to its simplicity and versatility. The restrained ring test is becoming widely used as a standard test method to assess the potential for early-age cracking in concrete mixtures. In the ring test the concrete is cast around a hollow steel cylinder. As the concrete dries, shrinkage is prevented by the steel ring, thus resulting in the development of tensile stresses in the concrete. The ring specimen
1 INTRODUCTION
In Saudi Arabia, the majority of concrete structures constructed more than three decades ago suffer because of lack of quality control and severe weather conditions. Concrete structures are prone to deterioration due to the very hot and harsh environmental conditions. Saudi Arabia covers a large area and is characterized by considerable differences in climate from one region to another, from the hot humid coastal areas to dry inland, and also by the extreme difference in temperature between winter and summer. Due to the hostile environment, the deterioration of concrete structures often takes place before their service life. Therefore, the structures deteriorate and need urgent repair.
