Waterproofing sodium bentonite geotextile

Code: PRS.0015

Components: 1

Appearance: Roll

Flexible waterproofing geotextile for active waterproofing of underground structures, containing a uniform layer of granular sodium bentonite, with a high montmorillonite content, equal to 5.0 kg/m², consisting of a needled geotextile fabric with nylon fibres interfaced with non-woven geotextile in weight 100%. CLAYTEX are supplied in two different sizes: CLAYTEX 120 = rolls of 1.20 x 5 m (6 m²), weighing approximately 32 kg per roll and CLAYTEX 250 = rolls of 2.50 x 20 m (50 m²), weighing approximately 270 kg per roll.

Linee di appartenenza

Certification obtained and Standards

Geosynthetics with barrier function

EN 13491

Geosynthetics with barrier function

General characteristics


Shelf-life: 12 months

Technical specifications

Fluid loss

13 ml

Longitudinal elongation at break

18.6 %

Breaking load longitudinal

17.7 kN/m


662 N/m

Dry thickness

6.5 mm

Swelling rate


Bentonite mass per area unit

5.1 kg/m²

Coefficient of permeability

< 3.5 x 10E-12 m/s

Available colours

- Beige

Packaging and dimensions

- CLAYTEX 120: 1 x (Roll 6 m²)

- CLAYTEX 250: 1 x (Roll 50 m²)


The products of the CLAYTEX line consist of natural sealants activated by water, with strong self-sealing properties. Their bentonite layer is continuous and uniform. The porosity of the protective and containment sheets is aimed at allowing a quick and proper hydration of the hydro-expansive material.

The bottom geotextile layer of the CLAYTEX products is made of polypropylene fabric of 115 g/m², while the upper geotextile layer is made of nonwoven polypropylene of 220 g/m².


1.1 m²/m²: Use 1 m² of CLAYTEX for every m² of surface to be covered, making sure to overlap the rolls by at least 10 cm at the edges of the mat to ensure permanent water tightness of the system.

Use fields

Waterproofing of underground structures in general, in the presence of groundwater risk. Waterproofing of waters containment basins, water channels and landfills.

Preparation of supports

The surfaces of the application walls must be free of protrusions, cavities, gravel pockets, through holes for formworks, discontinuities from construction joints etc. For this reason, they should be preliminarily reclaimed with anti-shrinkage mortar (REPAR family) or with bentonite-based preparations (CLAYGRAIN). The support must absolutely be compact, otherwise it will be necessary to pre-create a suitable concrete subbase upon laying the bentonite sheet.

Use method

The geotextiles should be placed with the polypropylene side facing the support (the darker side) and fixed by anchor nails with washers; in vertical walls, the installation must proceed from the bottom, after having made a suitable cement mortar cove, to be made preferably with OSMOCEM 447, at the corners produced between the base slab and the elevation wall, in order to facilitate laying the sheet.
Each mat must overlap with the adjacent one by at least 10 cm, arranged to ensure the vertical joints are staggered. It is essential to ensure the mats have an appropriate flap at the geometric discontinuity of the work, of the top of the structures etc. Pay particular attention to laying the bentonite sheets at the corners, wells, stairs, and reinforcement rods protruding from the floor slab.
Avoid proceeding with concrete covering works of bentonite mats in anticipation of heavy rains. In the impossibility of a timely backfill it is necessary to provide for the temporary protection of mats with polyethylene geotextiles of 100-150 g/m².
In case bentonite geotextiles have been installed outside the perimetral brickwork, do not backfill the excavation with material other than sand (sharp rocks, crushed by the weight of dry aggregates, could tear the bentonite sheet).
For more information please contact our Technical Service.

Permitted supports

- Bricks

- Cement-based or lime-based mortars

- Concrete

- Mixed walls (bricks and stones)

- Plasters

- Stone walls

- Tuff

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