B.R.T.A. Architects, Alkmaar
Type of treatment: polished
«Decomo relates the architectural story of a school frontage»
Decomo accepted the challenge of creating an artistic frontage for the new school building of Van der Meij College at Alkmaar in The Netherlands. During this unique project, the limits of applicability of a concrete material were explored and successfully expanded.
Boulevard of perceptions
Students of the new van der Meij College do not receive their lessons in classical classrooms, but in «perception rooms» accommodated as individual operations along a boulevard. The college has become a working building, where students «learn by doing» in a stimulating, safe and readily overseen learning environment. The expert educational and organisational outlook of the school has laid the foundations for the spacious design of this new building, all of it contained within a protective cocoon, namely, the frontage.
Birds' nest
From a distance, the frontage gives an overall impression of «marble», but whoever comes closer will clearly discover a tree-like structure in the relief. The tree is a symbol of life and of growth. The birds' nests in the tree are in front of the students, who are growing up together in a safe nest, are developing and when the time is ripe, spread their wings and enter the wide world. Altogether 391 birds, 117 nests, 1523 branches and 3046 leaves are incorporated in the relief.
Decorative concrete
Decomo can certainly retrace the design philosophy of the college, but the challenge primarily resided in its high technology feasibility. Decomo stands for the engineering production and assembly of frontage components with decorative relief features.
The snow-white colour was achieved by the use of white cement and a snow-white additive. The surface was polished and after fitting in place, protected by depositing a water-repellent coating in order to prevent soiling.
Challenging relief
For the casting of the 180 components use was made of only two rubber mats. Because of the positioning of the mats in different places in the shuttering, no two components are alike..
The relief must pass smoothly over the different components and the pattern must not be interrupted where joints have been planned. This called for extreme accuracy during the process shuttering and assembly
The Decomo relief also played a part during polishing. In order to prevent damage, recesses in the components were filled with a calcareous material (readily removable), in order to achieve flat surfaces, which can be polished with ease.
Sandwich panels
Due to the degree of difficulty of the relief, 4 months were spent on the preparation of the shuttering. Production occupied 3 months, but the major saving of time was recorded during assembly. Thanks to the use of sandwich panels, this only occupied 2 months.
Sandwich panels are laminated components with a concrete layer on both faces. The outer cavity leaf is 110 mm and the inner cavity leaf 140 mm thick; between these elements is 70-mm thick insulation. The panels combine very good insulating properties with high thermal capacity.
Ready to click in
In the case of this project, Decomo opted for non-loadbearing sandwich panels fastened on bearers and recesses in the floor. The frontage was thereby separated from the building shell and the time needed for the best possible engineering phase was available without adversely affecting the planning of work. As soon as the contractor had completed the structure, Decomo assembled the frontage panels, in order to make the building wind- and waterproof.
After assembly and during the work of finishing Cecomo ensured that all joist had been insulated in order to prevent the formation of thermal bridges and to be able to exploit as well as possible the insulating function of the panels.
Example of a school
The frontage components with their marked relief, determine the character of the building, but what the passer-by cannot guess at and what Decomo has encountered only too clearly, is the fact that during the project the aesthetic choice has far-reaching implications, ranging from the engineering, through casting, shuttering and polishing and as far as and including assembly and finishing.
Now that the building is standing, it is a brilliant example of a school, the result of excellent teamwork and of the manner in which Decomo explored and successfully expanded the limits of applicability of concrete material.
