Gleitkanten

Gleitkanten is a German term that translates to "slide ridges" in English. It is a visual phenomenon observed in concrete and other cement-based materials. Gleitkanten typically appear as small, narrow bands or lines of darker grey or black coloration on the surface of a concrete slab or wall.

The formation of Gleitkanten is attributed to the movement of fine particles in the concrete paste during the early stages of concrete curing. As the concrete sets, the finer particles, such as silicates and lime, migrate to the surface, creating the dark-colored bands. This process is thought to be influenced by factors such as the mixture design, water content, and temperature.

In architectural and construction contexts, Gleitkanten are considered an imperfection or defect in the concrete surface finish. However, some architects and designers have intentionally left Gleitkanten visible in their designs to add a distinctive texture and visual interest to the concrete. Consequently, the term Gleitkanten can be found in various architectural styles and design movements, including Brutalism and Expressionism.

Gleitkanten can also be observed in other materials and applications, such as in mortar and plaster. While their appearance is generally considered undesirable, they can be mitigated through modifications to the mix design or the application process. Gleitkanten are often more pronounced in areas where there is a high degree of moisture or where the concrete has been subjected to significant stress or movement.

Geometry and aesthetic appeal play significant roles in the design considerations of Gleitkanten. In some cases, they are sought after, especially in designs that emphasize the natural look and the texture of the construction material.