Unlike in North America where UHPC is mostly associated with bridges and the accelerated bridge construction system, in Denmark UHPC is used mainly for prefabricated slim balconies, external walkways, and staircases. UHPC has become the concrete material of choice for many Danish architects when creating slim, elegant structures. The material allows the architect a large degree of freedom when shaping the construction, and the constructive principles used for mounting can be akin to both regular concrete elements and a steel solution.

Frederik Boysen, Project Manager, Hi-Con, Denmark

Hi-Con has been a leading manufacturer of precast UHPC solutions in Denmark since the company was founded in 2001, producing primarily the products mentioned above. In recent years, however, a new use has found its way to the market: facades. 

Facade elements in UHPC have a broad spectrum of applications as anything from external sunscreen cladding to sandwich elements with cast-in insulation. The advantages of using precast UHPC facade elements are discussed in the following. The first three examples each highlight a key characteristic of the material through their application. The last two are examples of facades where the load-carrying capacity of the UHPC has been utilized to decorate the facades with balconies.

Beyond the geometrical freedom it grants the architect, the advantages of using precast UHPC facade elements are numerous. For example, waterproof UHPC ensures a watertight facade with only the joints exposed. A part of shapability is size and a large factor in constructing with UHPC is the rapid mounting process. The elements’ primary restriction in size is transportation. This means that it is possible to mount upwards of 40 or 60 m2 with each element. Lastly, the high strength makes systems wherein balconies are carried by the facade directly feasible. All this makes for a material that is flexible in application, that can have advantages in securing the right construction thickness, that can provide a waterproof facade and a short mounting period.

At Odense University both compressive and tensile high strength was needed to enable the architect to have a largely perforated facade. In this example, the elements are cast in a large number of variants that could be created by simply changing positions of circular mold parts or exchanging these in the flat rectangular mold. Elements were 2.4 by 5.4 m.

At Strandingsmuseum St. George a large element size was essential to the architect’s vision. Cladding elements that span the entire height of the structure was mounted on brackets. All elements were cast against a rough wooden mold to allow the wooden structure to be visible in the up to 15.4 m long elements.
At Herningsholm Technical College a thin external UHPC slab on a framework of integrated beams made it possible to reduce the thickness of the wall structure which allowed for the more square meter on the same property. A variety of single-sided panels with cast-in insulation and sandwich elements with cast-in insulation was used. All types utilize a 3 cm thick front slab. Elements were varied greatly in size, with the largest being up to 2.4 by 7.7 m.

At AArhus on the harbor of Aarhus UHPC balconies in a band along the entirety of the outward-facing facades results in an impressive facade. The Balconies are coupled with hidden L-columns, making the facade expression reminiscent of insitu-cast decks protruding the glass exterior. Balcony-elements are cantilevered 1,8 m from the facade and are up to 9.6 m in length. The largest element was created for the top canopy; a triangle of 4.9 by 10 m, assembled from three precast elements. The elements were cast together with CRC JointCast (Hi-Con solution) on site.

While still on the drawing board, this project in Copenhagen sees the renovation of two 665 m2 gabels (facades). The gabels are part of a larger renovation project. The gabels will have a wooden structure and act as the supporting structure for the new stairs, and the 2.4 m cantilevered UHPC balconies. On the pictures, a full view and a section of the rough draft is shown. The renovation of this facade, and the addition of new balconies is to be done entirely in UHPC, only horizontally supported by the existing building through simple brackets. The facade elements are up to 3.7 by 7.1 m.

Hi-Con is specialized in high strength concrete. The average cube strength of Hi-Cons UHPC is 160 MPa and always include high strength stainless steel fibers. The company uses durable concrete to create beautiful stairs, balconies, bridges and facade elements for unique building projects throughout Europe.
The head office is 20 km. north of Aalborg. The Hi-Con brand also includes branches in the Netherlands, Norway, Sweden, and Finland.