Waterstop Extra bentonite waterstop
Waterstop Extra hydrophilic bentonite waterstop, 20 × 25 mm section, supplied in 30-meter packs for sealing concrete construction joints and pour joints.
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 Istituto di Sperimentazione e Ricerca – Laboratorio Geotecnologico (Institute of Testing and Research – Geotechnical Laboratory). The test report is available to download below.
Key characteristics
Product: Waterstop Extra hydrophilic bentonite waterstop. Composition: natural sodium bentonite and polymer binders. Cross-section: 20 × 25 mm. Pack: 30 meters total, supplied as 5 rolls of 6 meters each. Color: 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 labor 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.