Cellflex: Bitumen Impregnated Fibreboard Expansion Joint Filler

Product Overview

Cellflex is a compressible, non-extruding, bitumen impregnated fibreboard expansion joint filler supplied in sheet form. It is specifically engineered to form and fill expansion joints in in-situ concrete construction across a wide range of structural applications.

Key Applications

Cellflex is suitable for forming structural expansion and separation joints in the following applications:

• Concrete pavements and floors
• Roads, ramps and runways
• Pedestrian areas
• Concrete retaining walls and bridges
• Concrete basement structures and subways
• Joints between in-situ and pre-cast concrete construction

Technical Specifications

Material Composition

Cellflex features a distinctive composition that combines durability with functional performance:

Property	Value
Bitumen Content	35%
Density	377 kg/m³
Form	Compressible sheet
Water Absorption	Less than 15%

Mechanical Properties

Property	Value
Compression	2590 kPa
Recovery	Greater than 70%
Standards Compliance	ASTM D1751 (Compression & Recovery Test)

Key Advantages

Cellflex offers several distinctive benefits that make it ideal for expansion joint applications:

• Easy to handle, cut and tamp – Simplifies on-site installation and adjustment
• Resilient – Maintains functionality under repeated compression cycles
• Non-extruding under compression – Prevents displacement and protrusion from joints
• Durable performance – Maintains structural integrity over extended service life

Critical Limitations

Sealant Compatibility

Cellflex must only be used with bitumen-based sealants. This is a critical specification requirement. The mobile fractions of bitumen present in Cellflex can degrade elastomeric sealants, making them incompatible for use with this product. Elastomeric sealants must not be applied over Cellflex, as chemical degradation will occur.

Application Instructions

Installation Method

When Cellflex is used to form an expansion joint in in-situ concrete, it shall be placed against the shuttering on the concreting side before the concrete pour begins.

Alternatively, Cellflex may be bonded to existing slabs or previous pours using suitable adhesive, providing flexibility for retrofit applications.

Storage Requirements

Cellflex presents a very slight risk of spontaneous combustion if stored long-term in wet conditions. Therefore:

• Store under cover in dry conditions
• Protect from prolonged moisture exposure
• Maintain dry storage environment to prevent combustion risk

Supply Options

Cellflex is available in both sheet and strip sizes to accommodate various joint width requirements:

Sheet Sizes

• 2.20m × 1220mm × 12mm (FC761300-UNIT)
• 2.44m × 1200mm × 9.5mm (FC700351-UNIT)

Strip Sizes (Various Widths)

• 60mm, 75mm, 100mm, 125mm, 150mm, 200mm, and 300mm widths
• Standard length: 2.44m
• Thickness: 9.5mm

All strip sizes are supplied in 9.5mm thickness with a standard length of 2.44m.

Key Performance Characteristics

Cellflex demonstrates excellent performance characteristics for its intended purpose. The product's resilience ensures it recovers after compression cycles, while its non-extruding property prevents it from bulging out of joints under load. The recovery greater than 70% indicates strong elastic behavior, enabling the product to return to its original dimensions after compression stress is relieved.

The relatively low water absorption (less than 15%) provides some resistance to moisture penetration, though the product is not designed for fully water-immersed conditions.

Important Considerations

Before using Cellflex, consult the complete Safety Data Sheet (SDS) and Technical Data Sheet (TDS) available from the Fosroc website. Application and performance data may change over time, and proper understanding of all product specifications is essential for successful installation and long-term performance.

References

• [1] Fosroc_Cellflex_TDS.pdf