Concrete, the "marble of the Modern Age", has arrived as a cutting-edge 21st century construction material. Hardly any other material has changed more in the public's perception in recent years: The gray material used to build the monotonous monstrosities of years past is now a material in high demand among architects looking for a pure aesthetic quality. Exposed concrete in particular is currently experiencing a true renaissance.
Yet this extraordinary construction material still has much to offer, with not only aesthetes but engineers as well have recently focusing intensively on it. Once low-tech it has become a high-tech construction material. Technical innovations and developments in the field of concrete production are spearheading the path to a new, exciting future. Tailor-made varieties such as self-compacting and ultra high performance concretes promise filigree constructions and a type of architecture that hitherto seemed unfeasible. Together with the manifold surface design possibilities, these concretes offer infinite room for planners' creativity. Textures, colors - almost anything is possible, even translucent concrete.
And it is not only architecture that has rediscovered the feel and visual qualities of concrete. An increasing number of premium brand producers are also designing their products with the aesthetic qualities of this building material and in their advertisements are increasingly favoring the clear design of concrete buildings. Concrete is cool and elegant, innovative and high quality. At the same time it is discreet and unobtrusive, yet always lends structures additional strength and definition. Proof of the extent to which concrete is "in" and reflects the zeitgeist.
The following provides details on some of the current developments and trends in concrete production:
Self-compacting concrete was conceived in Japan in the late 1980s. There is no need to vibrate SCC, it is able to aerate through gravity alone. This is made possible by a modern high performance concrete plasticizer with a polycarboxylate base. Its selling points are its great strength and durability. SCC can be used to make complex geometric shapes and homogeneous surfaces with low porosity. The Phæno Science Center in Wolfsburg, designed by Zaha Hadid, was one of the first major buildings to be made with SCC. Now many others have joined its ranks. There is a particularly beautiful and sculptural object in northern Italy, the Seebad Kaltern swimming complex in Caldaro by The next ENTERprise architects. Today, almost all cement and concrete producers offer self-compacting concretes.
High performance concretes are those with a high compressive strength. In order to maintain this, the concrete texture must be optimized. This can be achieved, depending on how the concrete is used, by minimizing the water/cement ratio, using effective plasticizers and achieving the optimum blend of aggregate and cement paste properties, such as by adding silica powder, microsilica or nanosilica. As well as its high compressive strength, high-strength concrete also demonstrates improved resistance to frost, and greater resilience. In architecture the Swiss ultra high performance concrete Vifort by Creabeton and the high performance binding agent Flowstone, made with Dyckerhoff white cement, are especially popular. The ultra strong material "Quantz", developed by G.tecz, is also excellent for structural and decorative use in a design, architectural or structural context. It combines outstanding material properties such as the compressive strength of steel and the resilience of ceramic with the potential of a cement-bound high-tech material with a great ecological and economic advantage. "Quantz" can be lent any form, whether used as strand casting material or cast in extremely thin forms. It can be used to produce both planar highly aesthetic objects with thin walls and ones with several curves.
In the field of architecture, ultra-strong concrete enables the use not only of slender components, but also angular textural finishes such as in the façade design of the RATP bus station in Paris as well as the most delicate structures, as impressively exemplified by the curtain wall of the "Dress Your Body" headquarters in Cormondrèche, Switzerland.
Fiberglass concrete and textile concrete
The thinner the better. Modern concrete is even able to satisfy the wish of many architects to design filigree structures. With fibre C, for example, the Austrian company Rieder has launched an innovative fiberglass concrete product that enables structural elements to be combined in a very slim way, and which are ultra strong despite the extreme thinness of their walls. These are thin, dyeable sheets between 8 and 13 millimeters thick that are very light and yet pliable. The SoccerCity World Cup stadium in Johannesburg as well as Zaha Hadid's Bridge Pavilion for the World Exhibition in Zaragoza were recently given fiberglass concrete façades. The Dutch manufacturer Fydro (DimamiC-CCC) and the Allgäu-based company Rudolph make special products using fiberglass concrete: 3D curved, pigmented, hydrophobic and with the optional addition of structures. Fiber-reinforced cement slabs, such as the well-known Eternit slabs, have long since proved their worth, but are still an integral element of modern architecture.
Photocatalysis is the magic word with the new, self-cleaning concretes. A special photocatalytic cement containing titanium dioxide is used in the production process. This functions as a catalyzer and converts air pollutants into harmless substances with the help of sunlight. Rainwater then cleans the building. There are several producers offering self-cleaning concretes, such as SAW in Switzerland. Richard Meier's well-known white Jubilee Church in Rome was built using sculptural prefabricated self-cleaning concrete components.
Self-cleaning concrete surfaces can also be produced using super hydrophobic (silicone resins or tetrafluoroethylenes) or super hydrophilic (lotus effect) surface coatings.
Building monolithic structures in these times of energy saving regulations is nothing if not a challenge. Yet even for this, concrete has innovative solutions to offer; so-called insulating concretes or infra-light concretes are a great help. For example, lightweight concretes such as these can be produced by adding foam glass beads by Liapor. For cases such as these the Swiss companies Misapor and Millcell (Vetrocell) also have foam glass concrete in their ranges. The recently completed Goethe High School in Regensburg, with its single leaf wall, is a good example of a structure built with insulating concrete.
Furniture design with concrete
Concrete is chic, in apartments as well. There is now an extensive range of kitchen worktops, sinks, coffee tables, dining tables and cupboards made from the hard material, which frequently display soft shapes and warm colors. There are even many different types of bathtub, be they solid or made of thin fiberglass concrete. The elegant items of furniture by the French designer Francesco Passaniti could virtually pass for classics. Those who prefer their furniture a little wilder can most certainly find something suitable at the Freiburg-based concrete producer Villa Rocca, with its roughcrete. The number of designers has exploded in recent years, be it material raum form from Hamburg or Werkform in Cologne, stayconcrete from Luxembourg or hightech from Munich. And the range of their creative home living designs using concrete is enormous. The Austrian manufacturer concreto is also getting in on the act in this field with its heat-resistant concrete fuoco, which has a brownish gray structure. The ecologically inclined are sure to like ecoX concrete by the American company Meld. Over 70% of its additives are sourced from recycled industrial material. And if it turns out to be somewhat lighter in terms of weight, Dutch Balsa Concrete, with its foam core, is sure to be of some help.
Nevertheless, even very simple concrete with no technological innovations has great visual appeal. A good example of this is the limestone concrete by Swiss-based Kalt Kies- und Betonwerk AG. Thanks to Jurassic limestone from the Mellikon quarry, this limestone concrete, with its beige hues, radiates a touch of warmth and coziness. After all, concrete means diversity.