Exposed aggregate concrete

Exposed aggregate concrete is concrete in which the aggregate is exposed by a special surface treatment.

Exposed aggregate concrete is used in the form of concrete slabs for floors or as decorative elements on facades. But even with three-dimensional objects such as planters, to washing Concrete can use.

In the production of washing the mold with a concrete retarder (such as sugar) is treated, or it is loaded with an impregnated paper retarder. At the treated areas of the surface of the concrete can not untie. After removing the formwork, the cement slurry are washed with a strong stream of water, possibly including the use of brushes. On the surface, the coarser aggregate only remains. Depending on the desired surface, the required aggregate is selected. Round ( unrolled gravel) or fractured ( basalt chips ) surface grain sizes are possible.

Aggregate concrete was used mainly in the 1960s and 1970s in architecture, for example in precast facades, exterior stairs, paving slabs or large planters. For stairs and sidewalks improvements of slip resistance were achieved by washing concrete, road, he is also installed. Meanwhile, wash concrete but is considered more and more as ugly, which is why he increasingly disappear from the cityscape and very little aggregate concrete is re-established.

Particularly in concrete slabs the Direktauswaschung is used. Immediately after pressing, the surface is treated with a high pressure water jet. The use of solidification retarders is unnecessary here. This method is usually applied only for small surface grains.