Difference between a contraction joint, isolation joint, expansion joint, construction joint, and a cold joint

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Difference between a contraction joint, isolation joint, expansion joint, construction joint, and a cold joint

Q. What is the difference between a contraction joint, isolation joint, expansion joint, construction joint, and a cold joint?

 

A. A contraction joint is formed, sawed, or tooled groove in a concrete structure to create a weakened plane to regulate the location of cracking resulting from the dimensional change of different parts of the structure.

An isolation joint is a separation between adjacent sections of a concrete structure to allow relative movement in three directions and through which all of the bonded reinforcement is interrupted.

An expansion joint in a concrete structure is a separation provided between adjacent sections to allow movement due to dimensional increases and reductions of the adjacent sections and through which some or all of the bonded reinforcement is interrupted. In pavements slabs on ground it is a separation between slabs filled with a compressible filler material.

A construction joint is the interface between concrete placements intentionally created to facilitate construction.

A cold joint is a joint or discontinuity resulting from a delay in placement of sufficient duration to preclude intermingling and bonding of the material, or where mortar or plaster rejoin or meet.

 

References: ACI 224.3R-95

Topics in Concrete: Joints, Movement; Concrete Fundamentals

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