Discussion: The trouble with concrete
It's not just what you do… The pleas of the cement industry have largely gone unheeded. No advertising slogan, no matter how catchy, has managed to really change people's prejudices against concrete. The reasons for its poor reputation are deeply rooted. For one, it has to do with the type of building made out of this material - quays, dams, silos and factories generally don't excite the public imagination. Right up until the late 1930s in fact, concrete was not allowed to show its true nature; it was hidden away behind brick facing, render and even granite blocks. A habit that reached its peak when the Ruff brothers clad their congress hall in Nuremberg with pale red granite, and Karl Meitinger dressed bunkers in Munich in neoclassical style. Apart from a few shining examples (Anatol Baudot's 1904 church in Montmartre, Max Berg's 1911 Centenary Hall in Breslau and Ernst Otto Oßwald's 1927 Tagblattturm in Stuttgart), much lauded by the architectural community, exposed concrete was by no means common, nor even acceptable to the general public. Traditional methods were considered far superior. It was the war that brought concrete out into the open. No time or money could now be wasted on "dressing up" bunkers, railway buildings, and power stations. These now began to show their true structure. Fate also brought the words "concrete" and "bunker" together for the first time. The unattractive look and associations of bunkers transferred in people's minds also to the material itself. Still today unloved architecture is easily dismissed as a "concrete bunker". Despite this image, concrete went on to enjoy a tremendous boom in the 1960s and 70s. There were three main reasons for this: Firstly, it was a recourse to the untainted heroes of the international modern, before the war. Secondly the many large-scale new construction projects - housing estates, schools, stadiums - simply could not be carried out cost-effectively in any other material. And thirdly, huge numbers of civil engineering projects - motorways, bridges, etc. - were being launched. Concrete itself paid a certain price for this new mobility, in terms of public perception of these grey "scars" on the landscape. …but how you do it. As these monuments to concrete euphoria began to age, it became obvious that more attention had to be paid to techniques and processes. Concrete was proving not to be as durable as it looked. Serious renovation work was necessary. The problems were many - poor reinforcement, exposed steel, water damage, spalling and structural weaknesses. Prestressed concrete in particular experienced a heavy fall from grace. Added to this was the question of aesthetics, which had a serious impact on the image of the material. Instead of an attractive patina, it developed patches of mould, efflorescence and dirt. If the general public had ever warmed to concrete, they turned away from it now. Realisation dawned that a whole host of issues had to be properly anticipated and handled. Including how to deal with it architecturally, as a structure, to achieve appropriate aesthetic effects. There was a lot still to learn. Education Today's climate of greater acceptance of exposed concrete owes much to half a century of experience with the material and to the results of modern research. The errors of the past are not to be repeated. Yet this recovery in image is still quite tentative. For the reasons why architects like concrete - material honesty, minimalism, abstraction, asceticism - are only appreciated within architectural circles. Out there, with the people who pay for and use these buildings, these criteria must first be explained, if they are to be understood at all, or even valued. The sensitivities of the professional and the lay person are still perilously far apart. Zwingmann's motorway church (1976-78), with its rich sculpted concrete decoration, is much more acceptable to many than Kulka's house of meditation (2001) at the Benedictine abbey of Königsmünster, in Meschede (ill. 5). So how do we set about achieving greater acceptance of concrete? Well it's certainly not by using terms like "material honesty" and "natural colour". To the uninitiated grey is just grey. Nor is it by avoiding the debate altogether and taking refuge in l'art pour l'art - the opportunities to indulge oneself like Peter Märkli (ill. 6) in the sculpture museum in Giornico are few and far be-tween. Architecture is after all a service to society. It seems to me that there are two ways of presenting exposed concrete to the aesthetically sensitive, not uninformed public. On the one hand concrete can be used in a finely balanced mix along with other equally carefully detailed materials, such as steel and glass. Here architects and clients are sure to find some arrangements that appeal to both. The second way is through perfection and abstraction. A eulogy to the artistry of Tadao Ando and his skilful handling of light and shade can open the way to an intellectual appreciation of concrete. Which could then lead to an acceptance of unashamedly all-concrete buildings like Ando's conference centre in Weil am Rhein (ill. 4) and his museum in Neuss (ill. 3). But actually living in a "concrete box" will for a long time remain the privilege of architects. A much more trained eye is required in the case of the church by Kister Scheithauer Gross in Freiburg (ill. 1). Powerful and uncompromising, this concrete monolith makes no excuses for itself, not even for its less than perfect surface quality. Schultes (ill. 2) and Bangert have also pushed concrete to its limits in creating their visions. Another heroic crusader for the concrete cause is Stephan Braunfels. Against much opposition he won the battle to use exposed concrete for the Paul Löbe Building (ill. 7) and the Marie Elisabeth Lüders Building, two buildings in the Bundestag complex either side of the Spree. As well as eulogising about the charms of concrete, however, he also laments the lack of expertise in the building trades in dealing with the material. Enlightenment The trouble with concrete is that it is such trouble. Special care has to be taken with the formwork, to stop things like discoloration; panels can only be used once; and calculating the pressures is a veritable science. Then you've got to get to grips with temperature ranges, vibration-compacting, hydrophobic treatments and the right timing for removing the formwork. Braunfels certainly had his problems with the government buildings. "You can always see the face powder," is his objection to any attempt at making good or covering up the raw face of the concrete. Diener & Diener, too, who built the five-storey extension to the nearby Swiss Embassy (ill. 8) rejected surface pigment applications, the concrete in their building owing its reddish-blue tint to aggregates delivered specially from the Vosges. Roger Diener is particularly proud of the fact that this monolithic, five-storey volume was poured in a period of just 30 hours. But even here, it was not possible to eliminate entirely the lines between the pours. The Swiss seem to know how to pour the finest visual concrete, and they've got the craftsmen to do it. Certainly in Vaduz (ill. 9), with the Kunstmuseum Liechtenstein, we are reminded of Tadao Ando's assertion that concrete is the "marble of the 20th century". Here the facade was ground and polished until the black-toned concrete (made with black basalt and coloured river gravel) looked like breccia marble. Its 60-metre long wall is a breathtaking sight; it was built entirely without expansion joints, thanks to prestressing. Success depends on the detail. On making the right choice of surface quality for the task and the dimensions in question, and then getting it right on site. If the architect wants to achieve the best results, there's simply no alternative to proper planning and proper monitoring.
