Exposed aggregate concrete
Washed concrete is a type of concrete in which the aggregate is exposed through a special surface treatment.
Exposed aggregate concrete is used in the form of concrete slabs for floor slabs or as a decorative element on facades. But exposed concrete can also be used for three-dimensional objects, such as planters.
Manufacturing
During the production of exposed aggregate concrete, the casting mold is treated with a setting retarder (e.g. sugar ) or paper soaked with setting retarder is inserted. The concrete cannot set at the treated areas of the surface. After removing the formwork, the cement slurry is washed out with a sharp jet of water, if necessary with the use of brushes . Only the coarser aggregate remains on the surface.
The desired structure and color of the surface is achieved through the choice of aggregate. Here, round surface grains, such as. B. unrolled gravel , granite or marble ( Carrara- wash concrete) , broken, such. B. Basalt grit in different colors and mixtures of different types of stone are used.
Direct washing is particularly useful for concrete slabs . Immediately after pressing, the surface is processed with a high pressure water jet. The use of setting retarders is unnecessary here. This process is usually only used for smaller surface grains.
use
Agglomerated concrete was mainly used in architecture in the 1960s and 1970s, for example for facades in prefabricated construction , external stairs, pavement slabs or large planters . In the case of stairs and sidewalks, exposed aggregate concrete has also improved slip resistance , and it is also used in road construction.
In the meantime, however, exposed aggregate concrete is increasingly viewed as unsightly, which is why it is increasingly disappearing from the cityscape and very little exposed aggregate concrete is produced. While some cities boast that the last exposed aggregate concrete buildings have disappeared, exposed aggregate concrete is making a comeback in advanced design and architecture circles.
See also
- Nagelfluh (a similar looking rock in the foothills of the Alps)
Individual evidence
- ↑ Use of exposed aggregate concrete on roads (PDF; 556 kB)
- ↑ a b Hannoversche Allgemeine on the disappearance of exposed aggregate concrete
Web links
- Moderne-regional.de - Essay by Benedikt Boucsein (moderneREGIONAL 2015) about exposed aggregate concrete in everyday architecture (accessed on July 26, 2017)
- beton.org - Zement-Merkblatt Hochbau H 8 1.2009; Title: Fair-faced concrete - surface design techniques; PDF (1.25 MB); Authors: Dipl.-Ing.Martin Peck & Dr.-Ing. Diethelm Bosold (accessed July 26, 2017)