Bentonite waterstop
Our bentonite waterstop MASTERSTOP for reliable waterproofing of construction joints as well as penetrations in concrete structures against water penetration. The swelling of the tape and the swelling pressure developed during the swelling process prevent water penetration.

The convincing advantages:
- Easy and safe installation
- No foundation curbs
- Self-injecting effect - The swelling tapes penetrate cracks and cavities
- Environmentally friendly
- No fittings or welding
- The swelling and shrinking process is reversible
- Dimensionally stable and not sticky
- No cuttings or oddments
- Safety proved by extensive testing
Further information on the topic of bentonite swelling tapes:
- What is sodium bentonite?
- Why bentonite swelling tape?
- What are the advantages of bentonite swelling tape?
Find the answers down below!
SKU | picture | Name | Description | |
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010011 |
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MASTERSTOP bentonite swelling tape 25x20 mm | Dim: 25x20 mm black General Building Supervisor Board Certificate CE label... | |
010012 |
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MASTERSTOP LONG TIME 25x20 mm | Dim: 25 x 20 mm, colour black coated bentonite swelling tape ... | |
010017 |
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MASTERSTOP bentonite swelling tape 20x10 mm | Dim: 20x10 mm black... | |
010020 |
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MASTERSTOP bentonite swelling tape 20x15 mm | Dim: 20x15 mm green... |
What is sodium bentonite?
Bentonite is a type of clay. There are different subtypes, such as: Sodium, calcium or potassium bentonite. The name changes depending on which chemical element is the predominant one. Bentonite is used in the construction industry for waterproofing buildings, among other things. Our swelling tapes are made of sodium bentonite and are characterised by their high swelling and water absorption capacity.
Why bentonite swelling tape?
Bentonite swelling tape is characterised by a very high and reliable swelling behaviour. They reliably seal construction joints that are temporarily or permanently exposed to water (e.g. groundwater) up to a water pressure of 5 bar.
Our MASTERSTOP bentonite swelling tape (dimensions 25 x 20 mm) swells in:
- Normal water (pH7) by up to 240%
- liquids that attack concrete by up to 120% and
- alkaline liquids by up to 220%.
Use in water exchange zones is possible without any problems. Bentonite swelling tape is available with a weather-resistant protective cover for installation regardless of the weather. This means that the bentonite well tape can also be installed in the rain. This is ensured by the protective cover, which seals it against rain and accumulated water for at least 10 days. This changes when it is set in concrete. The composition of the concrete causes the protective cover to lose its function after a few days, releasing the swelling tape and allowing it to seal the joint securely and permanently in the event of water ingress.
What are the advantages of bentonite swelling tape?
- Simple and safe installation
- No moulded parts and welds
- No upstands
- Swelling and shrinkage process is reversible
- Self-injecting effect - the swelling tapes penetrate cracks and cavities
- Dimensionally stable and non-sticky
- No waste or offcuts
- Environmentally friendly
- Safe through extensive testing