What are control joints in concrete?
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construction industry
Contraction/control joints are placed in concrete slabs to control random cracking. When shrinkage is restrained by contact with supporting soils, granular fill, adjoining structures, or reinforcement within the concrete, tensile stresses develop within the concrete section.
Keeping this in view, what is the purpose of a control joint in concrete?
Control joints are typically used in concrete masonry to reduce the occurrence of shrinkage-related cracking. A control joint is a continuous vertical joint filled with mortar, but with a bond breaker on one side so that tensile stress cannot develop across the joint.
Control joints are commonly found in concrete:
- Garage floors.
- Driveways.
- Sidewalks.
- Patios.
- Basement floors.
- House slabs.
Accordingly, what is the difference between a control joint and an expansion joint?
A control joint is used to reduce the occurrence of shrinkage in concrete, and it is usually a continuous, vertical joint filled with mortar. An expansion joint is a continuous or horizontal joint.
Space joints (in feet) no more than 2-3 times the slab thickness (in inches). A 4" slab should have joints 8-12 feet apart. Cut joints deep enough. Cut joints 25% of the depth of the slab.