Hollow block
A hollow block is a large-format building block for walls made of concrete or lightweight concrete with air chambers perpendicular to the storage area. In some cases, stones made of sand-lime brick (> 15% perforation) are also made as hollow blocks.
properties
Technical characteristics
The air chambers in the stone improve its thermal insulation . They are mostly rectangular. The air chambers are usually closed at the top so that the mortar connecting the stone does not fall through. In rare cases, they remain open and are used to guide static reinforcing structures through the wall. The air chambers are open on the underside, so that the mortar penetrates somewhat into the chambers when it is placed and stabilizes the wall horizontally. The cavities make it easier to halve hollow blocks with the mason's ax or to divide them differently.
The bulk density is mostly between 0.8 and 1.4 g / cm³. An F90 -Feuerschutz is achieved from just 17.5 cm wall thickness; Fire protection walls need 30 cm. By today's standards, hollow blocks as external walls require additional layers of insulation.
Dimensions
A hollow block (Hbn) is a five-sided closed brick made of concrete with chambers perpendicular to the bearing surface at a desired height ≤238 mm in masonry with Dickbettfuge or a target level ≤249 mm in plan stone masonry metallic and a cover above the chambers having a thickness of at least 10 mm.
Usual widths are 11.5 cm, 12 cm, 17.5 cm, 24 cm, 25 cm, 30 cm, 36 cm, 38 cm and 49 cm. So that the blocks do not become too heavy to wall, the wider stones are shorter than the narrower ones. The weights are mostly between 15 and 25 kg per stone. Typical proportions are (width by length in cm) 11.5 × 49, 25 × 38, 30 × 38 and 38 × 25. Grooves are often incorporated on the broad sides, often according to the tongue and groove principle. Some manufacturers also offer other dimensions.
commitment
Hollow concrete blocks have been around since the middle of the 19th century. A first patent for this comes from Great Britain on November 17, 1850. The inexpensive to manufacture hollow blocks were for a long time the predominant building material for exterior walls and load-bearing walls in single and two-family houses, mostly with a wall thickness of 24 or 30 cm. In the 1970s, they were more and more replaced by the better heat-insulating brick or aerated concrete blocks.
Today's thermal insulation requirements can only be achieved by relatively light bricks with economical wall thicknesses. Because the construction with light bricks results in constructional problems (e.g. increased risk of cracks), masonry exterior wall constructions are nowadays often made of masonry of a medium or heavy bulk density class and external thermal insulation composite systems .
Hollow concrete blocks are used as a cost-effective and easy-to-use solution, primarily in garages, halls, property walls or basement structures, where thermal insulation plays a subordinate role.
See also
literature
-
Ferdinand Werner : The long way to new building. Wernersche Verlagsgesellschaft, Worms 2016, ISBN 978-3-88462-372-5 .
- Volume 1: Concrete: 43 men invent the future. In particular pp. 295-302.
- Volume 2: cement and artificial stone. The triumph of the imagination.
Web links
- Hollow block - Leichtbeton.de , accessed on June 3, 2018.
Individual evidence
- ↑ Ferdinand Werner: The long way to new building. Wernersche Verlagsgesellschaft, Worms 2016, ISBN 978-3-88462-372-5 , p. 296.