Early age contraction of concrete may cause excessive cracking in restrained concrete structures within the first few days after casting. TJie magnitude and rate of development of early-age deformation of concrete are often not known reliably and restraint to shrinkage is often poorly modelled in structural design. Cracking due to restraint is often unavoidable in reinforced concrete structures and crack widths need to be controlled to meet requirements regarding water tightness, durability and aesthetics. Crack width modelling is typically performed using the existing standards and methods available in the literature. These methods and models are based on both experiments and different theoretical models of cracking of concrete. Most prediction methods define crack widths as the integration of the strain difference between the steel reinforcement and concrete over a transfer length for a single crack formation or over the crack spacing for a fully developed crack pattern. Tins paper discusses the approaches that are available in the literature with a view to determine the most reliable methods. The paper presents an analysis of causes and factors affecting early-age cracking and the concrete properties that are required to accurately model the mechanisms contributing to the cracking of concrete. Based on the most reliable method, assessment of cracking in existing structures is discussed.
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