We know the general principle that contraction joints in sidewalks should be cut at intervals that make individual panels approximately square. How frequently should an expansion joint be provided?
Portland Cement Association literature states that isolation joints (expansion joints) in flatwork "are required at points of potential stress for example, around rigid objects such as manholes, fireplugs and utility poles. They are also required at intersections of walks and drives and at points where slabs abut existing buildings or curbs. Isolation joints are not required at regular intervals in sidewalks and driveways."