Joint Design Flashcards

1
Q

Cohesive Failure

A

Tear down the middle of the joint due to lack of Sealant depth, usually because the backer rod was placed to shallow.

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2
Q

Adhesive failure

A

Excessive depth of Sealant due to positioning the backer rod too deep

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3
Q

Correct Sealant placement

A

Depth is 1/2 the size of the width.

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4
Q

What’s the minimum and maximum joint widths for CTS Products?

A
  • no smaller than 1/4”
  • no greater than 3/4”

2:1 width to depth ratio

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5
Q

Why are joints designed ?

A

Joints are designed to ensure sealant movement capability

- Movement allows for changing temperature conditions

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6
Q

What happens to joints in cold temps?

Hot temps?

A
  • Joints treated with sealant will ALWAYS experience compression at low temperatures.
    • Low temperatures increase the rigidness of the sealant
  • Joints sealed will ALWAYS experience lengthening or extension at high temperatures.
    • High temperatures increase the flexibility of the sealant
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7
Q

Explain Cold temperatures and joint placement…

A

Joint sealants placed at low temperatures will ALWAYS be more rigid during placement.

  • Low temperatures lower the viscosity (i.e., increase the stiffness) of the sealant
  • Extreme cold will result in rigid material that cannot be placed
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8
Q

Explain Higher temperatures and joint placement…

A

High temperatures increase the viscosity (i.e., increase the pliability) of the sealant

  • Extreme high temperatures will result in very fluid, potentially runny, sealant
  • High temperatures increase the viscosity (i.e., increase the pliability) of the sealant
  • Extreme high temperatures will result in very fluid, potentially runny, sealant
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9
Q

Define Backer rod

Explain the function of…

A

Backer Rod is required for proper joint treatment prior to sealant installation.

  • Backer Rod is foam material used in both vertical and horizontal joints.
  • Its function is
    • to prevent three sided bonding within the joint
    • allow for adequate movement
    • Help ensure proper depth of sealant placement
  • The size of the joint will determine the appropriate size of the backer ro
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10
Q

Movement Capability

A

Aka elongation characteristics

  • The elongation characteristics of the material indicate its ability to withstand movement before tearing, de-bonding or cohesive failure (tearing down the middle of the sealant placement).
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