What is the difference between Contraction Joint and Control Joint?

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    aagangchen (Edited )

    On a related note: A Contraction/Control Joint  is a depression to induce the cracks along the lines we choose, and not a complete separation. Expansion Joint is a complete separation. See link:

    Difference between Contraction, Construction and Expansion Joints (civilology.com)

    Gang Chen, Author, Architect, LEED AP BD+C (GreenExamEducation.com)

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    Lizann

    Hello.

    As I understand it, there is no difference. They are the different terms for the same condition. This is deduced from a question on Designer Hacks PDD practice problems.

    They reduce the sectional area making the concrete weaker in that location to guide any cracking that may occur from shrinking.

    Isolation joints are used where adjacent areas of concrete may move in three directions and where the formation of cracks is to be avoided.

    Construction joints are  the horizontal or vertical joints between 2 successive concrete pours. Joints are keyed to provide additional shear strength. 

    Keyed Joints keep reinforcement continuous & maintain alignment after concrete has cured.

    Cold joints are when a concrete slab is too large to be completed in a single concrete pour.

    The last type is the Expansion joint which is slightly different than an Isolation joint. Sometimes the terms are used interchangeably.

    I've provided way more definitions than what you initially asked for, but I've found it easier to remember the different kinds of joints.

    Best, Liz

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    Arjumand Anjum

    Thanks again Elizabeth :)

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    rebekkak (Edited )

    Please research in Ballast or another resource.  You should know all the different types - control joints, construction joints, expansion joints, and isolation joints.  It's in ballast p 21-24.

    Rebekka O'Melia, B.Arch, M. Ed, Registered Architect, NCARB, ​​Step Up ARE Coaching​​​

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    aagangchen

    I made a Youtube video on a related subject:

    What is the difference between expansion joints and control joints? 

    https://youtu.be/fYXotxt--38

    Gang Chen, Author, Architect, LEED AP BD+C (GreenExamEducation.com)

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    rebekkak (Edited )

    Please research in Ballast or another resource.  You should know all the different types - control joints, construction joints, expansion joints, and isolation joints for the exam.  

    Rebekka O'Melia, B.Arch, M. Ed, Registered Architect, NCARB, ​​Step Up ARE Coaching​​​

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