The properties required for ideal sealants are;
1. Adhesion.
  • Ease of application under construction conditions.
  • Resistance to slump and creep.
  • Low compression resistance.
  • Compatible with both surfaces.
  • Minimal shrinkage.

2. Resistance to weathering.

  • Water repellent.
  • Resistant to Ultra-violet radiation.
  • Heat resistant up to 80°C.
  • Cold resistant down to -20°C.
  • Mould resistant .

3. General properties.

  • Non-corrosive .
  • Flexible .
  • Gap-filling .
  • No primer needed.
  • Ability to accommodate shear movement in thin bands of sealant.
  • Resistant to ageing.
  • No maintenance required.
  • Long life expectancy ( more than 20 years).

Sealants are also known as cold solder because they perform the same function on metals that cannot be soldered with a lead/tin solder.

All soldered or sealant sealed laps and seams must be mechanically fastened for strength.

The sealant does not require significant total adhesive strength, but it should bond positively to both surfaces as a continuous layer. To ensure complete sealant cure, the width of sealant in a lap should not exceed 25 mm when compressed

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