Bentonite-rubber swelling joint, specific for usage with sea water

Code: PRS.0242

Components: 1

Appearance: Stripe

High performance hydro-expansive sealing waterstop for construction joints with safe hermetic seal for structures, masonry and foundations, made of a mixture of sodium bentonite, hydro-expansive rubber and special binding polymers ("hydrocarbon"), specifically designed to be used in contact with salt water or organic leachates. CLAYSEAL 25.20 SW has a rectangular cross section of 25x20 mm, packed in rolls of 5 m each.

Linee di appartenenza

General characteristics


Density: 1.4-1.5 kg/dm³


Hydroexpansive product: + 550 %


Shelf-life: 12 months


Temperature of use: -15 / +50 °C

Technical specifications

Longitudinal elongation at break

60 %

Sodium bentonite content

>75 %

Unit weight

0.83 kg/m

Available colours

- Red

Packaging and dimensions

- Box: 6 x (Roll 5 m)

- Pallet: 48 x (Box 21 Kg)


CLAYSEAL 25.20 SW is a simple and easy to apply sodium bentonite waterstop; it does not require any special preparations of the media, pre-shaped seats etc. It is easily fixed by nailing and does not require any special protection. In contact with water (even salted or polluted), it increases its volume through the formation of a stable colloidal system that guarantees the permanent hermetic sealing of the connection; the initial expansion is delayed through a retardant coating with respect to the first contact with water, to avoid deformations in the initial hardening phase of the fresh concrete.

The expansion of CLAYSEAL 25.20 SW in salt water or water with leachate and pollutant content, is at least 180% (just under twice its initial volume). Potential expansion in case of contact with clean water could be significantly higher (even of the order of 1000%).


1.1 m/m: Use 1 metre of CLAYSEAL 25.20 SW for each linear metre, being careful to place 5-10 cm of the product alongside the end/start roll points to guarantee the permanent water tightness of the system.

Use fields

Producing rigid construction joints (non-expanding) and safely and permanently hydraulic sealing connections in environments with salt water, sea water, organic leachate and pollutants of various kinds (for example landfills, biogas digesters, etc.).

Preparation of supports

Prepare the smoothest and most planar laying surface, using REPAR TIX to compensate for any inhomogeneity, and accurately remove crumbling, non-adhering, powdery parts.

Use method

Apply by hand the waterstop in sodium bentonite CLAYSEAL 25.20 SW in the provided position. The product should be secured with nails: a steel nail and a washer about every 20-25 cm. The sealing of joints between the waterstop beads is ensured by the simple approach of at least 10 cm and not by overlapping the ends.
For particularly complex applications, is available the specific cage of steel wire BENTONET, with square mesh of 13x13 mm, in profiles of 1 meter each.
The positioning must ensure a concrete covering of 10-12 cm in order to contain the expansive action generated by hydration.
Although the product has a delayed expansion of 48h, it is not recommended for use in cases of earlier time-frames or with excessive humidity (for example in the presence of puddles).

Application methods

- Apply by hand

- Hammer

Permitted supports

- Concrete

- Cement-based or lime-based mortars

- Prefabricated concrete

- Rock walls

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