5 important facts about Construction Sealants - Terminology, Purpose, typical applications, sealed material and Products

 

What’s the difference between a caulk and a sealant ?

A caulk is any low or intermediate performance compound. Typically being lower quality and having limited service lives. For example: Acrylic Latex, Butyl, Butyl Rubber, Co-polymers, putty etc. Life cycle: usually 3 – 5 years.

A sealant typically refers to a high performance compound having more expensive ingredients, little shrinkage, excellent weathering and UV resistance and providing long service life cycles from 10 – 20 years.

 

Purpose of Joint Sealants

1. Seal penetrations/joints between construction elements    

2. Prevent ingress of water/moisture to building interior or through joints/gaps

    Prevent water damage

    Prevent reinforced concrete corrosion

    Prevent structural steel damage

    Help prevent mould development

 3. Prevent hard materials or snow/ice from entering openings or joints..structural damage

 4.  Accommodate Movement

 5. Function as Part of an Air Barrier System

 6. Function as Part of a Vapor Retarding System

 7. Acoustic Control

 

Typical applications

1.High-rise and low-rise commercial buildings:

  Window perimeters

  Roofing terminations

  Expansion joints and butt-terminations

  Glazing

2. Plaza decks

3. Major Chains (Tilt-up) Exteriors

    Relaince Retail, Shopping malls- Inorbit, Patanjali Stores 

4. Institutional

    Schools, Courts etc

5.  Airport pavement runways and aprons

6. Bridge & Highway joints (DOT)

7. Commercial parking lots and flat work

8. Public Works

    Sidewalks (concrete)

9. Park Decks

10.  Waste & Water

      Submerged environments (NSF)

11.  Adhesive and bonding applications

      Industrial, Residential and commercial

 

Typical  Building Products and Materials which can be sealed 

Concrete

Masonry & Brick

Wood, Plywood, and Cement-Based Siding

EIFS (Exterior Insulation and Finish Systems)

Stucco

Stone, Manufactured Stone, Cultured Stone

Vinyl and Aluminum Siding

Painted Products

Foam Plastic Panels

Ceramic Tile

Metal Panels (Coated and Uncoated)

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Systems include Doors, Windows, Skylight

Popular Sealants used : Acrylic ,Polysulphides, Silicones, Polyurethanes, Hybrid , MS Polymers 

Popular Polyurethane Sealants : Sikaflex , Boss , Mccoy Soudalfex,  Anabond, Choksi , Fosroc  etc 

 

Joint Sealants – Terminology

ASTM C 920  is the standard specification for elastomeric joint sealants. It is made up of several ASTM test methods including:

Movement capability (ASTM C 719)

Sealant hardness (ASTM C 661)

Tack free time (ASTM C 679)

Adhesion in Peel  (ASTM C 794)

Sealant Hardness – ASTM C 661

Is a measure of a sealants ability to resist the penetration by a Durometer probe.

Rated on a scale from 0 – 100. The lower the number the softer the sealant. The softer the sealant the more movement it can take.

Conversely, the higher the number the harder the sealant is and the less movement it can take.

 Movement Capability - ASTM C 719

Measures the cyclic movement (extension [+] and compression [-]) of a sealant. Classified with the following movement classes

 +/-12.5%

 +/- 25%

 +/- 35%

 +/- 50%

 +/-100/50%

Stress Relaxation – is the ability of the sealant to absorb extension without incurring additional stress on the bond line to the substrate. Sealants that recover completely and rapidly from deformation usually have less stress relaxation than those that recover slowly.

Modulus

 Low Modulus Sealant – Creates low stress at the sealant bond line. Usually has a higher movement capability.

 Medium Modulus Sealant – Typically a general purpose sealant that can be used for the majority of elastomeric sealant applications

 High Modulus Sealant – Not used for moving joints, typically used for glazing applications