A Water Swellable Bar (25 x 20 mm) is a hydrophilic waterstop used to seal construction joints in concrete structures. It swells in contact with water to form a tight, compression-based seal, preventing water ingress through non-moving joints.
Its a rubber or bentonite-based sealing strip that increases in volume when exposed to water expanding to fill voids or gaps in concrete joints. The 25 x 20 mm size refers to the width (25 mm) and height (20 mm) of the strip.
Hydrophilic Rubber (EPDM, Polyurethane, or Natural Rubber Blend)
Chemically engineered to expand multiple times its original volume when wet.
Bentonite-Based Swell Bars
Use natural clay minerals that expand when hydrated.
Often contains sodium bentonite or superabsorbent polymers (SAPs).
| Property | Value |
|---|---|
| Size | 25 mm (W) x 20 mm (H) |
| Swell Ratio (by Volume) | 150% 300% (depends on formulation) |
| Material Type | Hydrophilic Rubber / Bentonite |
| Water Pressure Resistance | Up to 7 bar (depends on product) |
| Installation Surface | Concrete-to-concrete construction joints |
| Elongation | 200% 400% (for rubber types) |
Self-sealing: Expands automatically in contact with water
Reliable in complex profiles: Conforms to irregular surfaces
Easy to install: No welding, special tools, or adhesive required
Reseals if cracked concrete allows water to re-enter
Chemical Resistance: Many grades resist salts and mild chemicals
Basement retaining walls
Tunnels and underground tanks
Precast concrete joints
Sewage treatment plants
Water tanks and swimming pools
Box culverts and pipe penetrations
Surface Preparation
Clean and free from dust, grease, or loose particles.
Fixing
Use adhesive, nails, or metal mesh to secure bar to the surface.
Maintain continuous contact no gaps or breaks.
Concrete Placement
Carefully pour concrete without displacing the swell bar.
Avoid direct water contact before pouring concrete.
Would you like a product datasheet, installation detail drawing, or a recommended brand or supplier for this 25 x 20 mm water swellable bar?






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