18.03.2010
The third-largest largest mosque in the world is currently being built on the bay of Algiers. It has about 95,000 square meters of natural stone facade, boasts the highest minaret in the world, a dome of 50 meters diameter, and a Prayer Hall in which 35,000 worshippers can gather. The complex - which is expected to attract 120,000 visitors a day - is impressive in many respects. The project represents a unique challenge for the facade planners from DS-Plan. They are supporting a consortium comprising Jürgen Engel Architekten and the engineering firm Ingenieurbüro Krebs und Kiefer with the planning of the facade. In addition to the technical implementation, the historical, religious and esthetic aspects of the task make it a special challenge. For example, it was necessary to develop solutions that would allow traditional filigree Islamic ornamentation to be incorporated without delaying the project.
The most striking structure in the mosque complex, which was commissioned by the Algerian state, is without doubt the 264-meter minaret. The challenge for the architects is to face the outside of the tower with traditional Islamic filigree ornamentation while ensuring that the tower still has a sturdy appearance and is capable of withstanding external influences such as earthquakes and the extreme climate. The traditional carving of a facade made of natural stone - as traditionally worked with hammer and chisel - would, however, take several decades. The solution to the problem is a combination of technical expertise and elements from traditional Arab architecture.
The minaret: Fiber concrete instead of hammer and chisel
The Islamic ornamentation is being integrated into the facade by means of so-called mashrabiya. These are decorative wooden screens used in Arab tradition as windows and providing solar protection, light, ventilation and privacy. To allow the complex and detailed designs to be completed efficiently and within the scheduled construction period, the DS-Plan facade experts have developed a modern method: The mashrabiya are prefabricated using molded fiber concrete, a material that weighs less but is extremely robust. These artistic panels will be used to cover a facade area of 7,300 square meters on the minaret alone, with a total area of 15,160 square meters being applied throughout the complex.
On the minaret, the mashrabiya elements will be mounted on the outside of the 5.85-meter storey-height partially unitized double facade at intervals of one meter. The space between
the suspended natural stone panels and the four symmetrically arranged concrete cores of the tower is up to 80 centimeters. The new construction of the facade elements and the substructure, specially developed for an earthquake zone, take these unusual facade design requirements into account. In this way, the esthetic requirement to decorate the facade with Islamic mashrabiya elements designed to exact specifications is met with state-of-the-art technology.
The mosque complex: Huge amounts of natural stone
In addition to fiber concrete specified by the DS-Plan facade specialists for the minaret and some parts of buildings, the main facade material used throughout the mosque complex is natural stone - with a total area of some 95,000 square meters. The goal is to maximize use of local, durable materials and to use local companies and semi-skilled workers wherever possible.
A mosque on this scale is only planned once every millennium. The entire complex will have a gross floor area of some 440,000 square meters. The minaret, visible from afar, will house a museum of Islamic history, sky lobbies, a research center, and two viewing platforms. The complex also has a Prayer Hall, the central mosque park, a cultural center, a library, a boarding school, and many other facilities.
The Prayer Hall: A dome 70 meters high
The DS-Plan facade specialists are working on six buildings and always have to bear in mind the harsh climatic conditions such as relative humidity, the high salt content of the air, wind, and high temperatures. The specialists have also been closely involved with the Prayer Hall, which has a capacity of 35,000 worshippers. The dome, which soars to a height of 70 meters, also features the traditional mashrabiya elements. Here they are integrated in a manner unique in the Arab world: They are attached to the outside of the thermal shell of the dome like ribs, giving the impression of being an external support structure. The actual support structure is inside. Sunlight reflected into the dome - and which can be directed with a system of mirrors - creates a special ambience.
Construction of the complex, located to the east of the historic inner city of Algiers, is to start this year. The international contract award process for a prime contractor has just begun.
Picture credits
Visualization: emptyform, Darmstadt
