Rubber Waterstop Strips
1. Introduction
A hydrophilic waterstop strip, also known as a swelling waterstop strip, is a flexible sealant. It’s made from rubber or an inorganic mineral mix combined with hydrophilic swelling agents. Its working principle is active sealing. When the strip contacts water, it expands by 200% to 800%. This helps fill concrete joint gaps and ensures reliable watertightness. Product types are commonly designated PN (standard), BW (high-performance composite), and SP (self-adhesive). Hydrophilic waterstop strips work well for construction and movement joints. They are easy to install and offer excellent anti-seepage protection. Standardized mass production is available from manufacturers such as Hengshui Longxiang. For selection charts, test reports, or samples, contact a technical supplier for support.
2. Technical specifications (typical)
| Key parameter | Unit | Test condition | Standard (PN) | High-performance (BW) |
|---|---|---|---|---|
| Expansion ratio | % | GB/T 18173.3-2014, 72 h water immersion | 200–400 | 500–800 |
| Hydrostatic resistance | MPa | seal leakage test | ≥ 0.6 | ≥ 1.2 |
| Service temperature range | °C | continuous service | −20 ~ 60 | −40 ~ 80 |
| Size (width × thickness) | mm | caliper, JGJ/T 212-2010 reference | 20 × 30 (±0.5) | 30 × 20 (±0.5) |
| Chemical tolerance (pH) | — | 72 h immersion | pH 4–10 | pH 3–11 |
| Adhesion / bond strength | MPa | concrete interface pull test | ≥ 0.3 (typical) | ≥ 0.5 (typical) |
| Expansion rate (first hour) | %/h | 1 h immersion | 5–10 | 10–15 |
(Standards referenced: GB/T 18173.3-2014, JGJ/T 212-2010.)
3. Typical applications
3. Typical applicationsHydrophilic waterstop strips are widely used where active sealing is required. Example applications include:
Tunnels: Use BW-type strips that expand 500% in humid tunnel joints to stop leaks.
Water conservancy: High-performance strips for waterworks expansion joints (tested to 1.2 MPa).
Basements: Use PN-type (20×30 mm) for post-pour construction joints in residential basements. Adhere with bonding adhesive for strong waterproofing.
Water treatment plants: Use standard strips in sedimentation tank joints for stable service in neutral pH water.
Civil defense/protection works: Use SP self-adhesive strips for deformable joints. They allow for fast installation and meet high sealing requirements.
The hydrophilic waterstop strip swells when wet. This makes it great for projects with changing water levels or occasional dampness.
4. Installation and handling best practices
Substrate Preparation:
Remove laitance, dirt, and oil from joint faces.
Ensure flatness deviation is ≤ 2 mm per 2 m.
Allow the substrate to dry before adhesive application.
Cutting and overlapping: Cut to joint length; least overlap ≥ 50 mm. Apply the recommended adhesive to the overlapping surfaces. Then, press firmly to ensure good contact.
Bonding and fixing:
Apply adhesive to both faces.
Wait until it feels tacky, but not sticky.
Press the strip into place.
Compact it with a rubber mallet.
Avoid entrapped air or loose contact.
Protection and Mechanical Fastening: For vertical setups, add mechanical anchors or bolts to support adhesion. Prevent exposure to water within 48 hours after installation to avoid premature expansion.
Storage: Store in a dry, ventilated warehouse (relative humidity ≤ 70%); avoid direct sunlight. Shelf life is typically 12 months in sealed packaging.
5. Frequently Asked Questions
Q: How to select the correct model for a project? A: Use PN for ordinary basements (200%–400% expansion). Use BW for tunnels, hydraulic projects, and situations that need high expansion or pressure resistance (500%–800%). Choose SP self-adhesive types for fast application and narrow joints.
Q: What if the strip expands in storage?
A: You must discard the unusable expanded material. Keep products sealed; open packaging only on site immediately before installation.
Q: How to treat leaks at overlaps?
A: Ensure overlap ≥ 50 mm, apply adhesive, and press firmly. For critical areas, add a 50×50 mm patch strip over the overlap and seal with more adhesive or sealant.
Q: Can you use hydrophilic waterstop strips in high-temperature environments?
A: Standard PN types work at temperatures up to 60°C. For hotter areas, like boiler rooms or heated tanks, choose high-performance BW types that handle −40 to 80°C. Also, check the polymer stability with each thermal cycle.
Q: How do they compare to pre-embedded waterstops (rubber water bars)?
A: Hydrophilic strips are easier to retrofit and cost about 30% less. They work well for narrow joints (≤ 5 mm) but are not suitable for large-displacement joints.
6. Conclusions and engineering recommendations.
Conclusion: A hydrophilic waterstop strip offers effective waterproofing. It expands a lot when wet, preventing water damage.
Expansion typically ranges from 200% to 800%. Hydrostatic resistance varies from 0.6 to 1.2 MPa, based on the product grade. Product performance depends on correct selection, strict installation, and proper storage.
Engineering recommendations
Dual-parameter selection:
Match strip size to joint width (e.g., for a 10 mm joint, use a 20×30 mm strip).
Choose the right model based on media and pressure (select BW for chemical exposure or high hydrostatic load).
Reinforced overlaps for critical joints:
Apply adhesive.
Install 50 × 50 mm patch strips at overlaps in key structures.
Supplier qualification: Need GB/T 18173.3-2014 test reports. Also, get third-party verification. This helps avoid underperforming products with an expansion of over 200%.
For custom samples, adhesive compatibility lists, or local supplier directories, contact a technical supplier. They can help verify applications and provide on-site support.
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