New techniques can beautify concrete buildings

August 1, 2012 - 07:00

Unattractive concrete tenement blocks in suburbs have given concrete a poor reputation. But new techniques mean that concrete can be used for exciting construction projects and for building robust housing in places with difficult access.

A new thesis has studied a special technique for forming concrete using a robust textile reminiscent of very large and light bags used for shopping and transporting building materials. Among the advantages are that the form can be located at the construction site, so elements can be formed on site. (Photo: from the thesis)

Many suburbs are made up of endless series of unattractive concrete tenement blocks. But in the future these dull buildings can be replaced by exciting, sculptural structures made of a highly ornamented version of the grey material.

Using new techniques for forming concrete, architects and builders can now create very unusual buildings and erect strong, robust houses in places with very difficult access. Flexible textile forms can replace traditional rigid wooden forms, resulting in more versatile construction methods.

Draping, stretching and cutting textiles on forms before the concrete is poured into the forms results in organic and attractively ornamented concrete elements, walls and pillars that can even be made on site, says Anne-Mette Manelius, of the Royal Danish Academy of Fine Arts’ School of Architecture.

Manelius has studied the potential of using textiles as concrete forms and draws her conclusion in her PhD thesis, ‘Fabric formwork for concrete – investigations into formwork and stereogeneity in architectural constructions’.

“Many people see concrete as an ugly material with negative associations,” she says. “But I have studied hitherto unseen architectonic possibilities in concrete, as I can see beauty in the ugliness.”

Manelius adds, “Sometimes you get the feeling that architects are the only people who love concrete. But concrete is what you turn it into. And if the people who use concrete as a construction material really put their heart into it, you can see the loving result – as long as you forget the impression created by all the bad concrete architecture that also exists.”

New techniques give new possibilities
Building using concrete, in which completely identical concrete elements are typically formed at a factory and erected at the construction site, has not seen much development since concrete started becoming a popular construction material after the Second World War. Completely different and varying forms can be poured today using a new technique. (Photo: Colourbox)

When architects and engineers use concrete, they calculate the load-carrying requirements of the construction, design the necessary forms and decide whether and how to reinforce the concrete by casting iron rods in the material.

Concrete elements are cast in rectangular forms to ensure that each element is an exact copy of the previously formed element. This method means concrete is well-suited for building quickly, precisely, uniformly and cheaply.

But this method has its roots in a tradition that arose before advanced computer programming enabled architects and engineers to calculate geometry, load-carry capacities and shapes.

Manelius believes that the way concrete buildings are constructed can be changed without freezing the idiom in the heavy concrete elements that we have become really good at building with.

The method we use today typically involves casting many completely identical concrete elements at a factory and then assembling them at the construction site.

“Concrete is one of the most widely used construction materials in the world,” she says. “But today’s construction method hasn’t changed much since the use of concrete really took off after the Second Wold War, when there was a need to build a lot of homes in Denmark. Today, however, there are many computer programs that architects and engineers can use for precise calculations based on completely different forms.”

Rethinking concrete as a material
The technique is very lo-tech because you can use any type of robust textile. This means you can build robust houses in inaccessible locations – for instance in connection with rebuilding Haiti after the earthquake.
Anne-Mette Manelius

However, one of the challenges is making the forms and concrete structures that can match the advanced calculations and wild designs. Another challenge is to rethink concrete and where and how it should be used.

“The challenge is really to understand what concrete is as a material – and that actually applies to all construction materials,” says Manelius. “Another question that should be asked is related to the advanced, strong and cheap technical textiles that we can now use for making very light forms, with ornamental decoration if we want. These forms can be made on site – but they are so light they can also be made far away and sent by post. What does all this mean for concrete’s potential as a construction material?”

Lo-tech building techniques benefit the poor

To help answer this question, Manelius studied a special technique for forming concrete using a robust textile that is reminiscent of very large and light bags used for shopping and transporting building materials. This technique has a couple of advantages: the form can be taken quite easily to the construction site and the concrete elements can be cast on site.

“The technique is very lo-tech because you can use any type of robust textile,” she says. “This means you can build robust houses in inaccessible locations – for instance in connection with rebuilding Haiti after the earthquake,” she says.

“But it also means that poor people can have access to strong buildings without heavy machinery and expensive construction materials. This aspect has very wide-ranging perspectives and is very democratic.”

Possibilities and limitations thoroughly explored

In the forms, the woven patterns of the textiles used are transferred directly to the surfaces of the concrete elements. At the same time, the technique makes it possible to pour the concrete into many differently-shaped forms.

Facts

Concrete was used as long ago as in the golden age of the Roman Empire.

Many of Rome’s most complete ruins were built using a Roman version of concrete, including Hadrian’s masterpiece, the Pantheon, from about 126 AD.

The Pantheon’s cupola is still the world’s largest unsupported dome.

The first experiments with the technique were made as early as the start of the 20th century, using hessian textiles. But the technique didn’t really catch on.

For a thorough test of the building method, Manelius teamed up with 200 architect students who had used the technique, so the practical aspect of her research was achieved by experimenting from basics, exploring the technique’s possibilities and limitations.

In practice, the form for a wall will typically be made of a wooden skeleton and the textile will be stretched out across two sides. Ties are inserted to keep the form’s two sides in place.

In a very simple way, this makes it possible to create a variety of forms while retaining a degree of control over the material. The final result also demonstrates an organic symbiosis between the textile and the concrete.

“The students explored the method by building things like walls, columns, furniture and sculptures,” says Manelius.

“My task was to explain what was happening and what it means on a larger scale should the construction principles developed by the students for, say, furniture be used to construct a complete building. This is research through design, and it also means that the 200 architect students got a rather special experience from their first meeting with concrete, which you don’t know a lot about when you start at a school of architecture.”

Comparable to a water-filled balloon

Facts

Concrete is often described as artificial or fluid stone. It comprises cement and water plus a bonding agent – sand and stones (and any reinforcement) – that holds it all together.

She illustrates the technique using a water-filled balloon.

“The technique can be compared to having a water-filled balloon between your hands,” she says. “There is interaction between the fluid concrete and the form’s flexible membrane, the textile, and you as the designer, just like there is if you squeeze the water-filled balloon.” 

Her thesis studies the possibilities offered by the technique and includes suggestions about how it can be used in the future.

Manelius took an industrial PhD course sponsored by two businesses that use concrete in construction.

“My focus on is making the technology more widely available,” she says. “The uses are often very artistic, but it is also used by engineers who are very interested in details. I try to point out the possibilities offered by the technique and I hope my work will be the starting point of a mass of new projects.”

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Read this article in Danish at videnskab.dk

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Translated by
Michael de Laine