How to Install Water-swelling Rubber Waterstop Strips – Full Version

Primary Keyword: Water-swelling rubber waterstop strips Also Called:

• • Hydrophilic rubber waterstop

  • Bentonite waterstop

• Self-adhesive waterstop strips

• Rubber waterstop with injection tube

• Installation of waterstop strips for concrete joints

Overview: Installing hydrophilic rubber waterstop strips is a precise job. The main goal is to achieve strong, continuous adhesion with no gaps between the waterstop and the concrete. This ensures effective waterproofing and durability.

Success relies on:

• Thoroughly cleaning and drying the joint surface.

• Precisely placing and securely fixing the waterstop.

• Carefully treating joints and corners.

• Protecting the waterstop during concrete pouring.

• Ensuring full and dense concrete encapsulation.

1. Preparations — Foundation for Waterproofing Work

1.1 Materials & Tools Preparation

1.1.1 Materials Inspection and Acceptance

Before mobilization, it’s crucial to inspect and accept hydrophilic rubber waterstop strips. This ensures the waterproof system is reliable. Experienced installers need to check that waterstops match the design drawings and technical specs. This includes common sizes like 30×20 mm and 20×15 mm. They also must ensure that the lengths fit the required runs. Check the surface for flatness. Look for defects like cracks, missing rubber, air bubbles, contaminants, or scars. According to industry practice, surface defects deeper than 2 mm or larger than 16 mm² per meter are unacceptable.

Check that the release paper is intact. Also, make sure the adhesive layer is clean and fresh. If there’s any sign of weak adhesion, the product should be considered nonconforming. This means it needs to be replaced right away, with help from the supplier. Always ask suppliers for certificates of conformity, quality inspection reports, and production dates. This ensures traceability.

Pay special attention to expansion performance for water-swelling types. Choose slow-swelling waterstops per typical standards (e.g., GB50108). The 7-day net expansion must not go over 60% of the final expansion. Also, the final expansion should exceed 220%. This stops swelling too soon or too much while pouring concrete. It also guarantees lasting sealing performance. Check the grout/injection tubes in composite waterstops. Make sure the tubes are continuous and the connectors are intact. This ensures reliable grouting later. All acceptance results must be documented and signed by contractor, supervisor, and supplier.

1.1.2 Tools and Equipment

A complete set of well-maintained tools is essential. Basic cleaning tools include wire brushes, chisels or scrapers, and brushes or blowers for dust removal. Cutting and positioning tools include sharp scissors or utility knives for clean cuts. Avoid ragged edges, as they can compromise seals. For non-self-adhesive types, prepare cement nails or steel nails and hammers. Typical fixing spacing: horizontal construction joints 800–1200 mm; vertical joints 500–800 mm. For self-adhesive types, a small roller helps eliminate air and improves adhesion. For complex details like pipe penetrations and irregular shapes, use filler or sealant materials. Options include water-swelling sealants and sealing putty.

1.2 Technical Preparations & Personnel Requirements

1.2.1 Drawing Review and Technical Handover

Before work begins, hold a thorough drawing review (design, supervision, contractor present).

• Clarify where to place construction joints.

• Specify the waterstop model and specifications.

• Decide on the installation method: reserved groove or direct bonding.

• Coordinate with other waterproofing methods, like embedded stops or injection tubes.

Technical handover to site crews should be practical. It must include:

• Installation steps

• Material properties

• Acceptance criteria

• Safety requirements

Waterstops must be centered on the joint. They should be tight to the concrete surface, with no folds or voids. Overlaps must be at least 50 mm; butt joints are not allowed.

1.2.2 Personnel Qualifications & Training

Installers must be experienced and trained in underground waterproofing techniques.

Provide pre-work training on:

• Base preparation

• Cutting and fixing waterstops

• Protection during concrete casting

Emphasize correct use of protective equipment (helmets, gloves, masks) and site safety. Practical demonstrations and mock installations are recommended so crews can demonstrate competence before working on the structure.

2. Construction Joint Surface Preparation — The Key to Bond Strength

2.1 Substrate Cleaning and Chiseling

2.1.1 Remove laitance and debris

Remove all laitance, loose particles, dust, and contaminants from the joint surface. Use wire brushes, scrapers, chisels, and compressed air or a vacuum for this task. Laitance is weak and porous — bonding a waterstop to it will lead to debonding under shrinkage or external loads. Use cleaning agents to remove oil/grease and allow surfaces to dry completely.

2.1.2 Expose sound concrete substrate

Remove the weak surface layer until a dense, rough concrete matrix is exposed. Use chisels, grinders, or water-jetting as required, but avoid damaging surrounding sound concrete. A roughened substrate increases mechanical interlock and effective bonding area. After chiseling, verify substrate soundness by light probing — no loose particles should come off.

2.2 Substrate Drying and Defect Repair

2.2.1 Ensure substrate dryness and no standing water

Hydrophilic waterstops expand when they touch water. So, the substrate needs to be dry. This prevents early expansion and keeps the adhesive bond strong. Remove standing water and drain sources. If needed, use heaters or dehumidifiers. Keep doing this until the moisture content meets manufacturer limits. A typical guideline is less than 8% by weight. Protect installed waterstops from rain or construction water before casting.

2.2.2 Repair honeycombing, cavities and other defects

Fix any cavities, honeycombing, voids, or uneven surfaces using polymer-modified cement mortar or other approved patching materials. Pre-wet deep defects before applying repair mortar. Compact in layers. Allow full curing and drying before installing waterstops. For large cracks, rout and seal with elastic sealants or grout as specified.

3. Waterstop Installation — Core Procedures

3.1 Positioning and Initial Fixing

3.1.1 Determine installation alignment

Mark the joint centerline with chalk or snap lines. For vertical joints, extend the line from bottom to top; for horizontal joints, ensure level alignment. Avoid interference with main reinforcement. Plan runs and transitions at corners to prevent sharp bends.

3.1.2 Self-adhesive waterstop bonding method

For self-adhesive hydrophilic waterstops, peel release paper progressively (do not expose the full adhesive face) and press firmly along the line using the palm or a roller. Keep pressure uniform and focus on the edges to prevent lifting. Self-adhesive products allow fast, reliable placement without nails and reduce mechanical damage risks.

3.1.3 Mechanical fixing for non-self-adhesive waterstops

For non-self-adhesive types, use cement nails or steel nails with wooden battens or wire mesh. Typical nail spacing: horizontal 800–1200 mm; vertical 500–800 mm. To avoid direct nail penetration that damages the waterstop, employ a thin wooden batten or a pressure strip under the nail; alternately fix over a wire mesh. Ensure nails avoid rebar locations.

3.2 Joints and Corners

3.2.1 Overlap length and method

Never butt two ends together. Always lap ends a minimum of 50 mm. Best practice: bevel cut ends at 45° or compress ends to half thickness before overlapping to create a smooth transition. Press and compact the overlap to ensure continuous contact with substrate.

3.2.2 Reinforced joint sealing

For critical applications, first apply a compatible primer or adhesive to the substrate. Then, overlay the ends. After overlapping, seal the joint with hydrophilic grout or polymeric sealant to fill microgaps. Composite waterstops with injection tubes make sealing easier. Make sure the tubes are continuous through overlaps for future grouting.

3.2.3 Corner cutting and fixing

At internal corners, make a V-cut on the inner face of the waterstop to accommodate bending; for external corners, plan cuts that achieve a smooth arc. Add extra fixing points on the inner and outer corners. Also, use segmented pieces with overlapping joints for complex shapes. Ensure no gaps or stress concentrations are left.

3.3 Final Inspection and Adjustment

3.3.1 Check flatness and security.

Visually and manually inspect the entire run for flatness, wrinkles, voids, or lifted edges. The waterstop must be tightly adhered to or mechanically fastened with no loose sections.

3.3.2 Rework and re-bonding

If adhesion is poor, carefully lift the affected portion, clean and dry the substrate, then re-bond. For non-adhesive types, remove nails and re-fix with closer spacing or additional battens/mesh. Replace sections where the adhesive has been contaminated or lost.