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Adheseal Megaprene 40GG polyurethane sealant for expansion and connection joints
Adheseal Megaprene 40GG polyurethane sealant for expansion and connection joints

Adheseal Megaprene 40GG Polyurethane Sealant

Low-modulus polyurethane sealant for precast panels, pavement and perimeter movement joints. Flexible ±25% movement performance in a gun-grade joint sealant.

Vendor: Adheseal
SKU: MEGA40CGR/SSG
Availability: Out Of Stock
$12.24
$12.24
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Description  

Adheseal Megaprene 40GG is a gun-grade polyurethane joint sealant for expansion and connection joints in precast concrete, tilt-up panels, pavement and building perimeters. It cures with atmospheric moisture to form a flexible seal that accommodates ±25% joint movement without the rigidity of a cement-based joint filler.

Choose Megaprene 40GG when you need a lower-modulus sealant that can move with concrete and adjoining construction materials. Its Shore A 25 cured hardness suits movement joints where flexibility matters, while resistance to brief contact with oil and fuel makes it useful around appropriately designed pavement and car park joints.

Typical applications

  • Expansion and connection joints between precast or tilt-up concrete panels.
  • Pavement and car park joints subject to expansion, contraction and occasional contamination.
  • Perimeter weathersealing around compatible window frames, cladding and masonry interfaces.

Choosing and installing Megaprene 40GG

Prepare clean, sound joint faces and use suitable backing rod or bond-breaker tape to control depth and prevent three-sided adhesion. The joint design, substrate and exposure determine whether priming is necessary. Allow the moisture-curing sealant to cure before service or chemical exposure.

For public-area joints where a firmer, more pick-resistant cured seal is the priority, compare Adheseal PU50. Megaprene 40GG is the softer, lower-modulus option. It is not a substitute for a purpose-designed structural glazing sealant, and substrate compatibility should be confirmed on sensitive materials.

Common Questions  

How much movement can Megaprene 40GG accommodate?
It is rated for ±25% joint movement.

What temperature range does it handle after cure?
Its recorded service temperature range is -40°C to +80°C.

Can it be used in swimming pools?
Do not use it in internal swimming pools where chlorine exceeds 5ppm.

Can it be used on natural stone?
Only after a suitable stain-testing program.

Uses & Benefits  
Single-component polyurethane sealant for expansion and connection joints in precast panels, pavements, cladding and window perimeters. Accommodates ±25% joint movement. Low modulus of 0.4MPa at 100% elongation reduces stress at the bond line. AS 1530.3 indices are 0 ignitability, 0 spread of flame, 0 heat evolved and 0-1 smoke developed. Service temperature range is -40°C to +80°C after cure.
How To Apply  
Apply between 5°C and 40°C to clean, dry substrates. New concrete must cure for at least 28 days. Design joints at a 2:1 width-to-depth ratio. Internal joints require at least 5mm width and depth; external joints require at least 12mm width. For joints deeper than 10mm use open-cell backing rod about 25% larger than the joint width, or bond-breaker tape. Tool within approximately 5 to 15 minutes before skin formation. Clean uncured material with Xylene. Cured sealant must be removed mechanically.
Limitations and Safety Info  
Do not use in totally confined spaces. Do not use in internal swimming pools where chlorine exceeds 5ppm. Do not use on bituminous surfaces, natural rubber, EPDM, or materials that leach oils, plasticisers or solvents. Do not use for structural glazing or mirror bonding. Copper and brass may discolour. Stain-test natural stone before use. Do not apply where active moisture-vapour transmission may cause bubbling. Keep uncured sealant away from cleaning agents, solvents and alcohol.
Suitable Substrates  
  • Concrete, masonry, brick, stone and porcelain.
  • Timber and painted surfaces.
  • Compatible plastics, rubber and fibreglass.
  • Powder-coated surfaces and waterproof membranes.

Adheseal Megaprene 40GG Polyurethane Sealant Physical Properties

Adheseal Megaprene 40GG Polyurethane Sealant Physical Properties
Property Value
Curing System Moisture
Full Cure 3mm per 24 hours
Density Black 1.15, Others 1.16±0.02
Shore A Hardness 25 after 14 days
Movement Capability +/-25%
Tear Strength 6.5N/mm
Elongation >400%
Modulus 0.4 MPa @ 100%
Application Temperature +5°C to +35°C
Service Temperature -40°C to +80°C
Pot Life 25 minutes @ 23°C & 50% RH
Skin Time 60 minutes @ 23°C & 50% RH
VOC Content <1.5g/L
Shelf Life 18 months in original packaging
Storage Conditions Cool dry between 10°C and 35°C
UV Resistance 500h Good
Chemical Resistance Excellent for water, detergent solutions, moderately diluted acids and alkalis, petrol and oil for short periods
Fire Performance Ignitability Index 0, Spread of Flame Index 0, Heat Evolved Index 0, Smoke Developed Index 0-1
Specific Gravity Black: 1.15. Others: 1.16±0.02

Adheseal Megaprene 40GG Polyurethane Sealant - Use Cases

Here are some common examples on where Adheseal Megaprene 40GG Polyurethane Sealant used by our customers.

Construction

Building Expansion Joints

Sealing vertical and horizontal expansion joints in precast, tilt-up panels, or curtain walls requiring significant movement.

This sealant maintains an elastic, waterproof seal under cyclical stress, preventing cracking and joint failure.

  • ±25% joint movement
  • Pass ASTM C-719 (Mortar, Aluminium)
  • AS1530.3 Low Ignitability
  • >400% elongation at break

Civil Construction

Car Park Pavement Joints

Sealing concrete or asphalt pavement joints in car parks or driveways exposed to fuel spills and vehicular traffic.

Its high elasticity accommodates constant movement, while chemical resistance protects against intermittent fuel and oil degradation.

  • ±25% joint movement
  • resistant to intermittent fuel spills
  • ASTM C-920 Type S, Grade NS
  • Shore A hardness 25

Sheet Metal

Metal Cladding Lap Joints

Sealing lap joints in metal cladding, roofing, or aluminium fabrication where flexibility and weather resistance are crucial.

Its strong adhesion and high elasticity accommodate thermal expansion and contraction, preventing leaks and maintaining structural integrity.

  • ±25% joint movement
  • Pass ASTM C793 UV testing
  • Excellent adhesion to powder coat
  • Non-corrosive to galvanised steel

Glazing

Perimeter Sealing for High-Movement Facade Elements

Seal perimeter joints around windows, curtain walls, metal cladding, or precast/tilt-up panels where differential movement and long-term weather resistance are critical.

Its high elasticity absorbs significant building movement and thermal expansion, providing a durable, UV-stable, and paintable weather seal for exterior facade components against harsh Australian conditions.

  • Joint Movement Capability: ±25% (ASTM C 719)
  • Passed UV testing as per ASTM C793
  • Paintable with acrylic, oil, and rubber-based paints
  • Excellent adhesion to common building materials, including powder coat

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