Brown tub
Brown tub is a civil engineering term and describes a building waterproofing in which geotextile mats with a bentonite filling are used. The name comes from the brownish color of the bentonite.
Sealing system
The waterproofing made of bentonite and plastic sheeting originally comes from landfill construction. Bentonites are clay minerals with a high swelling capacity, which arose from volcanic ash and were named after a large site in Fort Benton, Wyoming / USA. This sodium bentonite binds 5 to 7 times that of water and swells unhindered to 12 to 15 times its volume, creating a gel-like mass. If this swelling is hindered by building loads or backfilling of excavations, a high swelling pressure arises in the material, which develops a sealing effect. This pressure also prevents water from flowing into the space between the seal and the structure (no circulation).
This sealing system is structurally impermeable to water with a permeability coefficient of k = 10 −11 m / s. To illustrate: the water impermeability of a 1 cm thick layer of sodium bentonite is only equivalent to a 100 cm thick layer of concrete. The swelling of the bentonite between geotextile layers, which are connected to one another by needling, does not trigger any pressure loads on the structure.
development
Technical use began in the 1970s when bentonite granulate was first filled into the hollow chambers of corrugated cardboard. These cardboard sheets were placed against the building walls to be sealed and under the building floor and protected with additional seals. Since the beginning of the 1990s, plastic fabric (so-called geotextile) was used instead of cardboard. These surrounding layers are connected to one another by needling and absorb the swelling pressure within this "pocket".
commitment
The sealing process is easy to use thanks to the simple way of laying the sheets and can be used largely independent of the weather. The high swelling capacity can compensate for irregularities on the building surface and compensate for cracks there ("self-healing effect"). The permissible crack widths can be in the order of magnitude of 0.3 to 0.4 mm, which is usual in concrete construction, while a crack width that is half as large is permissible for the white tank , which requires a correspondingly higher reinforcement content. The construction joints in the transition from larger building sections are secured in the brown tub with expansion joint tapes, which are also filled with bentonite, are placed on the outside and are accordingly easy to handle.
See also
Web links
Expertise
Leaflet
- Bentonite-protected concrete structures - brown tubs . Austrian Construction Technology Association (öbv)
Manufacturer information
- CETCO Germany GmbH, Löhne / D, VOLTEX-Braune Wanne
- Adicon Gesellschaft für Bauwerksabdichtungen mbH Rödermark / D
- adicon company for renovation and sealing technology mbH Zettling / A
- CEMproof AG, Sirnach / CH
- BPA-GmbH, Herrenberg / D
- Amcol International, IL / USA Voltex brown tub
- Dernoton, Heinrich Dernbach, Mülheim ad Ruhr
Individual evidence
- ↑ a b c Anton Pech, Andreas Kolbitsch (Ed.): Keller. Springer Verlag, Vienna, ISBN 3-211-23745-3 . books.google.de
- ↑ a b H. Moosbauer: Black tubs - white tubs - brown tubs. Sealing of structures against water pollution . ( Memento of the original from February 10, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF) In: Tiefbau , Vol. 112, No. 4, 2000, pp. 221–227, ISSN 0944-8780 .
