1.4.07 Building security for all – self-sealing water barriers for windows and doors

A large number of towns and communities have been affected by flooding in recent years. The floodwater gets into houses and often destroys all the furnishings inside. Windows and doors must be sealed in good time to prevent water escaping over banks from getting into buildings. There are already various protection systems available on the market, yet experience has shown that old buildings in particular are not sufficiently sealed. Scientists from the Saxon Textile Research Institute in Chemnitz therefore developed self-sealing water barriers for windows and doors for flexible and straightforward installation – even in old buildings with uneven walls – that can also be removed without any problems.

Conventional flood protection systems for windows and doors generally comprise protection panels that are either affixed directly to the masonry with pins and screws prior to a flood or inserted into pre-installed rails. The crucial thing here is that the gap between the panel and the wall is perfectly sealed so that there are no little openings or cracks for the water to access the inside. And yet – as experience from recent floods shows – this prevention is hardly ever implemented, a trait particularly prevalent among a large number of old buildings as the uneven masonry does not enable precise, impermeable sealing to be installed. Even rubber itself is not elastic enough in such cases, and silicone is not easy to remove from plaster, windows and door frames once the barrier system has been taken down.

Mineral sealing material

In light of the above, scientists at the Saxon Textile Research Institute in Chemnitz have been seeking more efficient and effective alternatives as part of the work on the BMBF-funded research project entitled “Selbstdichtende Wassersperren für Fenster und Türen” (self-sealing water barriers for windows and doors). And their solution? Mineral sealing materials that can be moulded by adding fluid and can thus flexibly adapt to unevenness. Loam and clay are examples of mineral substances that swell up when moistened and can be moulded into any shape. Used to fill special textile tubes and moistened before use, they can adapt to match the masonry perfectly. Tests have shown that bentonite is an extremely suitable sealant for this purpose. This stone is a mixture of various clay minerals and is particularly effective at absorbing water and expanding. The clay granulate used is extremely fine (grain size of 0.1 to 2 mm), making it easy to dispense and helping to prevent the funnel from blocking when filling the textile tubes (bridge-building). This granulate was therefore selected for use in the subsequent tests.

Produced in a single process

The textile tubes are to be filled with bentonite granulate during production so that the complete product is made in a single process. The scientists worked with representatives from Umwelt- und Maschinentechnik GmbH in Pöhl to test special machines used in textile processing that would be suitable for this. These included a circular loom, a circular knitting machine and a “Kemafil” machine. The latter of these can be used to implement a special procedure developed and patented by the Saxon Textile Research Institute, which enables a wide range of materials to be coated with a three-dimensional mesh structure. The sealing system is produced by shaping a non-woven material into a tube and securing with meshed threads, and simultaneously filling this with the mineral substances. The tests showed that a right-left small circular knitting machine was best at producing the seal for the barrier system.

Additional scouring protection

It has been demonstrated that textile tubes filled with mineral granulate are suitable for balancing out minor and major unevenness in walls and providing perfect sealing. This sealant must be moistened before application between the wall and panel. If a significant flow speed is encountered, additional scouring protection should be applied prior to sealing. A tube made from soft, recycled textile is suitable for this; it does not prevent water gradually seeping through to the seal, but it reduces the flow speed such that the mineral components are not washed away.

Benefits of the self-sealing water barrier

The self-sealing water barrier system is quick, flexible and straightforward to install without any pre-installation work required; it can be applied to all building types and removed again without any problems. As well as the mineral seal and scouring protection, the system includes metallic or non-metallic front panels affixed using a quick-release mechanism. This dispenses with the need to secure directly to the masonry with pins and screws. The perfect seal also means there’s no need for laborious resealing once floodwater has come up against the barrier.

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Technology

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