At the end of last year, the first United World College (UWC) in Germany was opened in Freiburg. In this High school, students from all around the world (71 nations) and from all social classes are taught equally. It happens so that a street child, a refugee boy and a professor’s daughter live and learn together for two years. They are selected solely according to their suitability and talent. A comprehensive scholarship makes sure that all students can afford to attend school. In the end, the visitors graduate from College with the "International Baccalaureate", a globally recognized university entrance qualification. The trails and supporting slopes were made by Adolf Braun KG, Teningen, using the white cement from CRH (Slovensko) a.s.
Learning in monumental spaces
The UWC Robert Bosch College is a joint project of the Robert Bosch foundation and the German foundation UWC. The school is also supported by the state of Baden-Württemberg. Overall, it offers 200 lesson courts, where 100 new students per year can attend the educational institution. These are taught in the monumental, lavishly renovated rooms of a former Carthusian monastery. To meet the daily boarding justice, those responsible authorities supplemented the baroque complex with a glass auditorium and a canteen with kitchen. Besides, with four teacher and eight student houses, a small housing estate was built, which clings to the steep slope of the terrain. The single buildings are connected by concrete paths and stairs of different width, which give the settlement the tranquil appearance of a mountain village.
Individual places and slope protections, which can also be used as a seat, underline this charm. The special feature of this infrastructure and the slope protection: It wasn´t built with the usual gray cement, but with white cement from CRH. If the concrete made of this cement is dyed, much more brilliant color results in comparison to the gray cement can be achieved. Also in terms of strength and handling, CRH White Cement is very good in comparison with its gray counterpart. With this successful choice of materials, combined with demanding installation methods, the planners emphasize how important the ways within the school community are.
The Adolf Braun KG from Teningen, a gravel and ready-mix concrete plant, took over the building process. It was also responsible for setting up the slope protections of stamped concrete. The production method of this seemingly archaic walls is now used rarely. The stamped concrete is a mixture of natural aggregates, water and cement. Compared to conventional concrete, it is much drier and not reinforced. The building material got its name because the processors stomped it until it became plastic and showed a closed surface, where a moisture film has been formed. Prior to the application of the next layer, typically after one day, the previous one is roughened, cleaned and moistened, in order to ensure the adhesion to the next one. If a layer can’t be made in a full length, the oblique recesses must be made, which are carried out in opposite directions from layer to layer in order to achieve a "toothing". It gives the stamped concrete elements their typical appearance.
In the construction of paths and steps, the authorities also resorted to a very down-home installation method: the broom finish. Here, the concrete is smoothed after installation and patterned using a broom. This creates a non-slip, rough surface, which offers increased slip resistance. At the same time, the ambient conditions and the work performance tremendously influence the result. To ensure a uniform appearance, the Adolf Braun staff had to bring a steady hand and a lot of experience.
Whereby the work was additionally aggravated by the topography, because the slope was quite steep and some machines could not even be used. All built concretes were mixed in the Adolf Braun KG plant. Because the elements are outdoors and unprotected, they are exposed to rain and must fulfill the exposure class XC4, among others. Due to the use of de-icing agents in winter, the requirements of the exposure classes XD3 and XF4 had to be met. When asked why the company chose the White cement from CRH, the superintendent Hansjörg Lorenz answered: "We already had very good experience with the CRH White Cement in another object. At that time we had to color the concrete and had gotten excellent advice from the company's employees. If you make such a good experience, you gladly get back to it again. "