Belzona 4521 (Magma-Flex Fluid)

An elastomeric expansion joint sealant for sealing joints in surfaces including concrete, brick and stone.  

Belzona 4521 (Magma-Flex Fluid)

A fast curing, 2-part flexible sealant designed to provide effective sealing of construction and expansion joints on concrete, stone, brick and other surfaces. This solvent-free material is a cost effective and high performance alternative to conventional mastics and sealants, providing joints with up to 25% flexibility and outstanding  weather and chemical resistance. It does not require any hot work and cures quickly, ensuring a safe and easy application.

Key benefits:

  • Provides expansion joint flexibility of up to 25%
  • Downtime reduction due to its fast curing properties
  • Reduced future maintenance and eliminates the need for expensive structural rebuild
  • Reduced health and safety risks as it is solvent-free
  • Application and cure at room temperature - no hot work involved
  • Excellent weather and chemical resistance against a wide range of chemicals
  • Easy to mix and apply manually with no specialist tools required
  • Excellent adhesion to surfaces including concrete, brick, stone and steel

Applications for Belzona 4521 (Magma-Flex Fluid) include:

  • Expansion joints sealing on horizontal surfaces such as floors, bridges, roadways, car parks and manufacturing facilities
  • Sealing of leaking joints in secondary containment areas
Key technical data:
Working life at 20°C (68°F)  45 minutes
Time to mechanical cure at 20°C (68°F) 4 days
Peel adhesion (ASTM D421) 26 pli (460 kgs/m) on blasted steel
Volume capacity 1612 cm³ (98.4 cu.in.) per 2 kg
Bonds to Concrete, stone, brick, steel, other Belzona 4000 Series materials and many more
Typical applications Elastomeric expansion joint sealant
Unit size 2 kg. Pack sizes may vary locally. 
Availability* Global

* All products are subject to regional restrictions. Check with your local Distributor for more information


More information:

For more information about Belzona 4521 (Magma-Flex Fluid) please contact us or find your local distributor.

You can apply to join Belzona Connect to access additional information including SDS and instructions for use.

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