Single Cast Fabric Formwork

December 3, 2010

Final Piece

Concept of a single cast structure:

Markings for reinforcement and guides for pouring as well as letters matching up to the holes in the top plate which came in very useful.

It is inevitable that architectural components require connections. However, the position of the connections is required to be in the best interest of the structural element, form, construction and aesthetics. One of the other reasons for pre-fabricating and casting separate pieces to fit together is for transportation, but of course concrete can be poured in situ! This posed a question about what was possible to achieve through the process of stitching – essentially tailoring fabric to generate a form.

We admired the past work done of the previous years, but were critical of the techniques used to connect fabric formed elements and argued that quite a few of the connections were infact unecessary. The qualities of fabric formed concrete is to use its inherent properties of the fabric to manipulate the plasticity of concrete.

Our position asked the question about what a beam and column could become. A beam needn’t be joined to a column as two individual pieces, could they be cast as a single element using sewing to stitch and shape the formwork using sleeves? We thought a more rational form might result if each element was cast together as a single entity using the qualities of the fabric to dicate the form. Our joint was made in the formwork itself.

The formwork complete and stiched laid out and marked up ready for hanging onto the frame. It can be folded up into a backpack.

Additionally, such a concept opens up new tangents and industrial possibilities in concrete construction methods. Suddenly a piece of fabric formwork can be specified (using the guiding principles), stitched in a textile factory off site, transported easily in a bag to a site, unfolded, hung into position with the use of simple scaffolding and minimal timber structure and cast on site as a single entity. Our aim was to prove this concept with a large free standing singularly cast enclosure: a wall with two columns.

Sleeve joint after casting.

The video of the frame and formwork construction, the pour and the final peel can be seen at the link below.

http://www.youtube.com/watch?v=-8rIywPBTtA

Finished casting.

End Elevation

Our prototype structure was successful with only a couple of complications due to not quite getting one of the columns verticle when we cut the holes – something that could be easily corrected by using a pole as a guide. As a result, the fabric at the sleeve wasn’t tense enough and risked a lack of concrete in the joint. Our solution was the tie the column back to the frame, to straighten it up and put the fabric into tension again. The result is a jaunty slender column that is quite appealing and has the remains of the rope marks on the surface as another reminder of process.

There is an even surface finish with very few imperfections over the whole surface. One area of imperfection however is towards the base of the wall that has not compacted fully because we were distracted by two burst cotton stitches, positioned to control the mass. The bottom most stitch survived, which proves the concept that it a simple 1cm square stitch can be used to control the mass and prevent it bulging. In the case of the other two, we determined that we weakened the fabric around the thread by over sewing it – making the stitch stronger than the cotton itself, resulting in a tare under the pressure of the concrete. We patched the breaches quickly, but the ‘bullet holes’ remain as evidence on the surface. However, it is interesting to see the difference in mass compared to the successful stitch at the base of the wall.

Another slight area of improvement is in the footings, where we were unable to access the concrete during the pour and probably didn’t vibrate the base enough to get a full compaction. The result is that some of the aggregate around the edge comes away and the concrete is imperfect around the base, but it is not in any structural danger.

The sleeve joints are expressed very well

View looking down the wall showing the bulges and the compression

It is possible to observe some beautiful abstract forms that evoke Dieste's work - all as a result of process and knowledge of technique

Looking through the structure. Detail of the surface finish and stitch pattern visible

It is fascinating to walk around the structure and look through the structure at different angles to appreciate the slenderness and the geometry. A space is defined by the structure, that gives an architectural language determined by the positioning of material.

 

In the context of our unit’s title Distructive Technology: Material Immaterial – the discussion that formed a critical part of our design process, that now only exists as notes and sketches, represents an immaterial property of a material concrete structure. In the process we have developed a language, a code, to work with this material and discuss its process and potential wtih other people. We have developed an understanding between material and immaterial.

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4 Responses to “Single Cast Fabric Formwork”

  1. This is fascinating. I am intrigued by the type of fabric you used as the form. Can you tell me what the finished dimensions are? The structure is very ‘biomorphic’ –Gaudi-esq. Wonderful

    • Hi Jill. Thanks for your comment. The fabric was simply thick (and quite heavy) cotton – it was the cheapest roll of left overs from the local fabric shop! It needed to be fairly thick because at that scale a thinner cotton might have deformed too much or torn under the pressure of the concrete around the top.
      The finished structure was about 7ft tall and covered about 2m x 1m floor area (basically 2 pallets!), but the thickest column diameter was only about 25cm or so. I recall the dimensions of the fabric used were about 10m x 3m. (If that’s what you meant.) Hope that helps. I’ve been meaning to update the blog for a while. I might get round to putting some images of some projections we beamed onto the structure, that you might be interested in. Richard.

      • Hi Richard,
        Thank you so much for the information. I would love to see some more images and the projections sound very interesting too. I am exploring ways to use fabric myself (mainly lycra as it has a wonderful capacity to stretch creating finished structures that are haphazard in shape) as supporting stuructures in my sculptural work (MA @ Sunderland University) and have found your ideas inspiring. I did not remove the lycra, and used plaster (which comes with its own limitations!) so I may try concrete as an alternative. Keep posing – I would love to see more. Thanks again.

  2. I have posted the projection images. Hope they’re of interest. We attempted using plaster (only once, for a test maquette) and we found it much more difficult to control than concrete – because it set so quickly – we should have used sand and cement for a small model (about 50cm high, with thin, 3 – 6cm diameter legs,for example.) Tip of the day – if you’re thinking of experimenting with fabric formed concrete is to remember to vibrate and rub the surface of the fabric as throroughly as possible to remove the water and draw the finer particles to the surface.That way, you obtain a really detailed and more durable surface texture – even using a standard – aggregate, sand, cement mix. Hope that helps!

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