October 1 2007

Graphic Concrete

Graphic Concrete is a Helsinki, Finland, based company that "offers a new way to produce a patterned concrete surface." The graphics are applied using a retarder applied to the surface of a membrane that is applied to the face of the concrete during forming/hardening. Here are the fascinating details about how this product is produced:

Graphic Concrete is based on a patented invention by interior architect Samuli Naamanka that involves applying a surface retardant to a special membrane in order to create the desired pattern on concrete. The membrane’s high level of rigidity makes it ideal for the production of large concrete surfaces. The membrane can also be used without the surface retarder for the production of fairface surfaces.

The membrane is 3.1 meters wide, which means that it can be used in the production of regular height façade elements without the need for joints. The length of the membrane is mainly limited by the maximum allowable weight of a roll, so it can be hundreds of meters long if necessary.

The surface retarder applied to the membrane slows the setting (hardening) of the concrete to the desired depth in specific areas. The unset surface part is usually washed away from the cast the next day, revealing the aggregate contained in the concrete. The washed surface stands out from the surrounding unwashed concrete surface due to its roughness and the contrasting color of the exposed aggregate. Altering the application area of the surface retarder makes it possible to create the desired patterns on the concrete. The surface can also be velvet smooth or completely exposed.

The normal depth of the pattern is usually the so-called fine exposure, i.e. about 1 mm, but shallower or deeper exposures are also possible. The cement can also be pigmented, which provides the color of the fairface surface. The aggregates can be a variety of different colors, which are then highlighted in the exposed areas.

The accuracy of the method makes it possible to duplicate the bitmap made from a photograph, in which case the minimum diameter and distance between the dots can be as little as 2 mm.

Here is a link to the product page.

And below are some photos of the installed product:

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