Joints in Concrete Construction

Restrained volumetric changes result in strains and ensuing stresses that lead to cracking. For a concrete system to be viable long term, it is essential to reduce the magnitude and extent of cracking by imposing artificial crack locations through the use of joints that relieve the stress levels and sometimes reduce them to a negligible magnitude. In essence, such joints can be viewed as artificial cracks. This chapter utilizes American Concrete Institute (ACI) committee reports and standards on this subject as a background, particularly ACI 224.3R, Joints in Concrete Construction (ACI Committee 224, 1995), and ACI 350, Environmental Engineering Concrete Structures (ACI Committee 350, 2006). Informational discussions on this subject are also utilized from the references provided at the end of the chapter.