Mapei Idrostop 25

Idrostop 25 – Hydrophilic Expanding Rubber Waterstop 20 x 25mm

Idrostop 25 is a pre-formed hydrophilic expanding rubber waterstop designed to create watertight construction joints in concrete structures. It gradually expands when in permanent contact with water, forming an active barrier against water penetration.

Please call for other sizes which are available 01268 472358

20x10 mm (Idrostop 10) 20x15 mm (Idrostop 15)

It is suitable for civil, industrial and hydraulic construction, including construction joints between concrete sections and contact joints between different materials. Unlike Idrostop B25, Idrostop 25 is an expanding rubber waterstop and does not contain bentonite.

Key Benefits

• Hydrophilic expanding rubber waterstop
• Designed for watertight construction joints
• Pre-formed flexible profile
• 20 x 25mm profile
• Gradually expands when exposed to water
• Creates an active barrier against pressurised water
• Suitable for positive and negative water pressure
• Does not contain bentonite
• Suitable for repeated expansion and contraction cycles
• Suitable for aggressive water environments
• Suitable for civil, industrial and hydraulic construction
• Can be fixed using Idrostop Mastic, nails or screws
• Suitable for difficult-to-access construction joints
• No waiting period before concrete casting when mechanically fixed

Applications

Idrostop 25 is suitable for watertight construction and contact joints in:

• Concrete base-to-wall joints
• Joints between concrete pours
• Contact joints between different materials
• PVC pipes passing through concrete
• Steel pipes passing through concrete
• Swimming pools
• Sewage-treatment tanks
• Water reservoirs
• Hydraulic structures
• Tunnels
• Dams
• Drinking-water reservoirs
• Concrete structures with dense reinforcement

Technical Information

• Product type: Hydrophilic expanding rubber waterstop
• Form: Pre-formed strip
• Material: Acrylic polymer-based expanding rubber
• Size: 20 x 25mm
• Product: Idrostop 25
• Expansion after 24 hours: Approximately 45%
• Expansion after 2 days: Approximately 70%
• Expansion after 3 days: Approximately 82%
• Expansion after 7 days: Approximately 120%
• Water impermeability: Up to 5 atm
• Elongation: 70–100%
• Shore hardness: 25–30
• Temperature stability: -30°C to +50°C
• Maximum joint width: 7mm
• Storage: 12 months
• Packaging: 6 x 5m rolls per box
• Total per box: 30 linear metres

Installation

Idrostop 25 is installed onto a clean, solid substrate within the construction joint. It can be secured using Idrostop Mastic or mechanically using suitable nails or screws.

When Idrostop Mastic is used, a 24-hour waiting period is required before concrete casting. When mechanically fixed using nails or screws, no waiting period is required before casting.

The product should not be installed while the structure is immersed in water, and free water should be removed from the installation area before application.

Frequently Asked Questions

1. What is Idrostop 25 used for?
Idrostop 25 is used to create watertight construction joints in concrete structures, including civil, industrial and hydraulic applications.

2. Is Idrostop 25 a bentonite waterstop?
No. Idrostop 25 is a hydrophilic expanding rubber waterstop. It should not be confused with Idrostop B25, which is a separate bentonite-based product.

3. What size is Idrostop 25?
Idrostop 25 has a 20 x 25mm cross-section and is supplied in 5m rolls. Six rolls are supplied per box, providing 30 linear metres.

4. How does Idrostop 25 work?
The rubber profile gradually expands when it comes into permanent contact with water. This expansion creates an active barrier that helps prevent water from passing through the construction joint.

5. Can Idrostop 25 be used in aggressive water conditions?
Yes. Idrostop 25 is designed to maintain its performance through repeated expansion and contraction cycles and is suitable for aggressive water environments.

Important Limitations

Idrostop 25 should not be installed while the structure is immersed in water. Free water should be removed before installation.

The maximum specified joint width is 7mm. The installation surface must be clean and solid and should not be heavily contaminated with acids or solvents.

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