Béton brut

Béton brut (French pronunciation: [betɔ̃ bʁyt]) is architectural concrete that is left unfinished after being cast, displaying the patterns, textures and seams imprinted on it by the formwork.

Le Corbusier coined the term béton brut during the construction of Unité d'Habitation in Marseille, France built in 1952.

[4] The essence of the philosophy is seen in the imperfections of béton brut which stem from the idea to create an aesthetic based on the exposure of a building's components, including the frame, sheathing, and mechanical systems.

When Corbusier coined the term, he was specifically responding to board-marked concrete, which he used to construct many of his post-World War II buildings.

It is important to use the same type of wood throughout the job, especially on larger buildings where the molds may get repeated uses, because the lumber can absorb moisture, which may possibly affect the color of the concrete.

Boston City Hall (1968), an example of brutalism using béton brut
Detail of the Royal National Theatre (1976) showing the grain of the formwork
Example of large board form concrete formwork, constructed to create a complex concrete wall form with the raw concrete aesthetic of béton brut
Closeup of board form concrete
Examples of béton brut seen at the Bauhaus Museum Weimar