Waterstop Extra bentonite waterstop
Waterstop Extra hydrophilic bentonite joint, 20 × 25 mm section, supplied in 30-metre packs for sealing concrete construction joints and pour joints.
Waterstop Extra hydrophilic bentonite joint
Waterstop Extra seals construction joints and pour joints in concrete structures. On contact with water, the joint expands and forms a barrier against infiltration, even under high hydrostatic pressure.
What it is and how it works
Waterstop Extra consists of about 75–80% natural sodium bentonite and 20–25% binding matrix made from butyl rubber and special polymers. When it contacts water or moisture, the bentonite expands in a controlled, multidirectional way. Its expansion exceeds 300% of its initial dry volume, allowing it to fill voids, cracks and irregularities in concrete and form an active, permanent waterproof seal. The product passed tests by the Institute of Testing and Research – Geotechnical Laboratory. The test report is available to download.
Key characteristics
Product: Waterstop Extra hydrophilic bentonite joint. Composition: natural sodium bentonite and polymer binders. Cross-section: 20 × 25 mm. Pack: 30 metres total, supplied as 5 rolls of 6 metres each. Colour: black. Free expansion: over 600%. The joint withstands significant hydrostatic pressure, retains its shape before hydration and does not expand prematurely in atmospheric humidity. When confined in concrete, it resists wet/dry cycles and does not deteriorate over time.
Benefits of Waterstop Extra
• Active, permanent sealing: expansion fills cavities and adapts to micro-cracks that may form in the concrete. • Quick, easy installation: no welding or complex equipment is needed; secure the joint with nails and washers, the recommended method, or the specific adhesive. • Adaptability: flexibility allows installation on irregular surfaces. • Chemical resistance: the joint resists agents commonly found in soil and groundwater. • Lower costs: installation reduces labour time and future maintenance costs. • Structural safety: gradual, controlled expansion avoids damaging stresses in the surrounding concrete, including young concrete.
Applications
The joint is suitable for waterproofing: • Vertical and horizontal pour joints in reinforced concrete structures. • Construction joints in foundation rafts, retaining walls and slabs. • Underground structures: basements, garages, lift pits and technical rooms. • Hydraulic works: drinking and non-drinking water tanks, swimming pools, canals, treatment tanks and pipelines. • Tunnels and underpasses. • Pipe penetrations and other elements passing through concrete. • Joints between precast concrete elements.
Who it is for
The product is intended for construction companies and contractors, waterproofing specialists, structural and architectural design studios, swimming-pool and hydraulic-works builders, and precast-concrete manufacturers.
Installation and storage
Preparation: clean and dry the concrete surface and remove dust, debris and loose material. Installation: unroll Waterstop Extra, position it centrally within the pour thickness, and secure it with steel nails and washers every 25–30 cm or with the specific adhesive. Joints: butt the ends together or overlap them by about 5 cm and press them together; welding is not needed. Concrete cover: provide at least 7–8 cm on every side to contain expansion pressure. Pour: place the next concrete pour without leaving the joint in standing water for a prolonged period beforehand. Storage: keep the product in a dry place, away from direct sunlight and moisture.
For professionals
Tests by the Institute of Testing and Research – Geotechnical Laboratory assessed the performance of Waterstop Extra.