Nitoseal PU400 - Technical Specifications and Features

Product Overview

Nitoseal PU400 is a high-performance, low modulus elastomeric joint sealant and adhesive based on polyurethane technology. It cures through exposure to atmospheric moisture to form a waterproof and durable seal, making it ideal for exterior applications and trafficable floor joints.

Primary Applications

Nitoseal PU400 is designed for use in:

• Trafficable floor joints - suitable for foot and light vehicle traffic areas
• Water retaining structures - metal or concrete water retaining structures
• Concrete infrastructure - joints in concrete culverts and pipes
• Metal frame assembly - building assembly and cover plates
• Structural connections - bolted lap joints
• Penetrations - sealing pipe penetrations in walls and floors

The product also serves as a substrate joint sealant following the application of Nitoflor PU600 flooring systems and can precede the application of Nitoproof 210 in waterproofing applications.

Key Design Characteristics

Joint Width Design

Nitoseal PU400 is designed for sealing movement joints between 10mm and 35mm wide, with capability to seal joints down to 5mm and up to 50mm under suitable conditions.

The width to depth ratio should be maintained at:

• Minimum depth of 10mm for joint widths between 10mm and 20mm
• 2:1 ratio for joint widths greater than 20mm

Movement Accommodation Factor

• ±12.5% (total 25% movement accommodation)

This relatively modest movement capability distinguishes it from other polyurethane sealants, making it suitable for joints with controlled movement.

Physical and Performance Properties

Property	Specification
Form	Smooth, non-slump paste
Tack-free Time	40 minutes (±10 mins) at 23°C, 50% RH
Cure Rate	24 hours to 3mm depth
Hardness	40 Shore 'A' (ISO 868)
Modulus @ 100% Extension	0.30 - 0.40 MPa (ISO 8339)
Elongation at Break	>400%
Tensile Strength	2 - 2.5 N/mm²
Service Temperature Range	-40°C to +70°C
Application Temperature Range	5°C to 35°C
VOC Content	105.6 g/litre

Chemical Composition and Base Technology

Nitoseal PU400 is formulated using polyurethane technology as its primary binder system. This polyurethane base provides:

• Excellent flexibility and elastomeric properties
• Low modulus characteristics for movement accommodation
• Moisture-reactive cure mechanism
• Weather resistance
• Durable waterproof sealing

Surface Compatibility

Nitoseal PU400 offers excellent primerless adhesion to:

• Concrete
• Timber
• Metals
• Ceramics
• Brickwork and masonry
• Most coating surfaces

While primers are not required, adhesion can be improved with optional primers such as Primer 21 for porous materials or Primer 4 for non-porous materials. Primer 13 must be used on porous surfaces if the sealant will be water immersed.

Advantages and Benefits

• Tough and abrasion resistant - provides durable edge protection
• Suitable for wide floor joints - ideal for trafficable applications
• Excellent primerless adhesion - reduced surface preparation requirements
• Low stringing - clean application with smooth finish
• Low odour - improved application environment
• Weather resistant - performs in diverse environmental conditions
• Easy to gun out - efficient application using standard sealant guns
• Water immersion capability - suitable for water immersed applications when used with appropriate primer
• Drinking water compatible - safe for use in contact with drinking water

Supply and Packaging

Nitoseal PU400 is commercially supplied in:

• 600 ml foil sausages in cartons of 12
• Available colour: Concrete Grey
• Product code: FC920121-600ML

Coverage Information

As a practical guide for project planning:

• One 600 ml sausage will seal 3 metres of 20mm × 10mm sealant bead

Storage and Shelf Life

• Shelf life: 18 months from date of manufacture
• Storage conditions: Dry conditions between +10°C and 25°C with 55% relative humidity, away from direct sunlight and moisture
• Packaging requirement: Original, unopened packaging essential for shelf life maintenance

Standards Compliance

Nitoseal PU400 has been tested to comply with AS4020:2018 Australian standards specification, as documented in AWQC Report 390492. Copies of this compliance report are available on the Fosroc website.

Application Method

Nitoseal PU400 is applied using:

• Standard 600ml sealant gun for controlled extrusion
• Sealant is extruded firmly into joints to ensure complete contact with joint faces
• Smooth finish can be applied if necessary with a spatula
• Tools must be cleaned immediately after use with Fosroc Solvent 10

Limitations and Restrictions

Not suitable for:

• Swimming pools - Nitoseal SC600 is recommended for these applications
• Bituminous surfaces - Nitoseal MB175 is recommended as an alternative
• Painting - Although polyurethane sealants generally accept acrylic painting, plasticizer migration may occur over time. Fosroc recommends Nitoseal MS250 when painting is required

Bond Breaker Requirements

In all joints, a bond breaker must be used to prevent sealant contact with the back of the joint for optimum performance:

• Shallow joints: Self-adhesive polyethylene bond breaker tape
• Deep joints: Backing strips such as Expandafoam or Hydrocell

Priming Requirements

While good adhesion can be achieved without primers on most surfaces, priming is recommended for optimal performance:

• Porous substrates: Primer 21 for general use; Primer 13 for water-immersed applications
• Non-porous materials (metals): Primer 4
• Water immersion: Primer 13 is mandatory

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References

• [1] Fosroc_Nitoseal_PU400_TDS.pdf
• [7] Fosroc_Expandafoam_Open_Cell_TDS.pdf
• [8] Fosroc_Expandafoam_TDS.pdf