Final Assignment: Catenary vault

For my final project, I wanted to work with textiles and gravity, inspired by Gaudi’s studies of self-supporting pillars and vaults. I would like to learn more about catenary – the physical term for the idealized curve, and how it can be used for making vaults. I believe that it now is possible to again use curved vaults in architecture, which have not been so popular for quite some time.

I wanted to make a self-supporting vault, casted upside down. The idea was that by hanging the fabric mould – the concrete would move into the most ideal curve for the vault, and as such be self-supporting. The process is described below:process.jpg

For my prototype I simple stapled two pieces of stretchy jersey fabric together and let them hang, filled with concrete. It seemed to work very well, but the casting had not fully dried in the right picture, so the fabric was not removed.

For the final product a template was made and the jersey fabric cut accordingly. The mould was hanged from each corner of the box and then filled with concrete. By now, I realized that the final product would not be rounded, rather more rectangular. The concrete mixture followed the give recipe for fabric casting, but extra water was added to make the mixture more fluid to fit into the mould.

After three days, the casting was removed from the box. When turned upside-down the casting could luckily support itself. However, it seems as if the casting has broken in the top – where the strain on the mould was the highest and the hole on top was the biggest. As such, the casting is probably in two pieces. Furthermore, it seems as if the concrete has not yet dried as a thin layer of concrete follows when pulling off the fabric. Perhaps in a few days the fabric can be more easily removed.

final product finished

The final product looks good (although with the fabric still on) and is self-supporting. The breaking is most likely due to the fabric mould that probably was too thin in the lowest-hanging parts. The size of the hole on top also plays a big part in the breakage. Had the hole been smaller the breakage might not have occurred. Also – the two pieces of fabric should probably not have been exactly the same size. Rather, the lowest hanging piece should have been larger and as such allow for more concrete further down – strengthening the casting. Perhaps the lower hanging textile could have been a stretchy jersey and the top fabric a more sturdy woven fabric.

casting worked well – had not dried when casting finished product

Finished casting:
Fabric mould had too big of a hole – should be decreased
Mixture had extra water to increase fluidity

Finished casting has not dried – fabric cannot be removed yet
Finished casting has probably broken in two pieces
Structure is self-supporting (yay!)


Group 5 – assignment 5

We made two separate moulds. One origami with sharp edges and one with rounded and doubled curvature. Both were made with thick paper.

When we mixed the cement we noticed that it was way too thick to get in between the larger aggregate. Hence, we added more than the doubled amount of water. With 2 kg cement and 1,2 kg water we agreed that the mixture was a flowable enough and could sink through the coarser aggregate. We still had to carefully mix the aggregate with the slurry inside the paper models, and we also shook the whole container as much as we could, so that the paper models would not be deformed.

The resulting models shows that the slurry still didn’t fill the models enough. The origami model lost its lower part, however the edges came out as sharp as the paper model. The larger model came out somewhat deformed. Part of the model lacked cement altogether. We expected that the aperture would still hold, but the finer aggregate in this part filled with cement anyhow, perhaps the paper broke somewhere in the middle.


Assignment 04 Fabric Cast




Our group chose the topics hydrostatic pressure and mixed material.

Hydrostatic pressure
We built a mold of mdf board to which we attached a piece of stretchy fabric, and on top of that a piece of knitted fabric. We poured/stuffed the concrete mix into the mold so that the gravity would shape the finished model.
The pattern showed, but not as much as we expected. We didn’t find the perfect balance between the hydrostatic pressure and the stretchiness of the textile.
Mixed material
For the mixed material assignment, we attached a less stretchy textile between two wooden boards. Underneath these were attached wooden sticks to fix the concrete in the desires size. Our purpose was to stitch the finished piece of concrete to two pieces of wood. To make holes in the concrete we fixed shorter wooden sticks with duck tape, as shown in the picture, and then poured the concrete into the mold. When the concrete was cured we stitched the finished piece together.
Both the fabric and the wooden sticks were easy to remove.

Assignment 03 – fluid form – group

Assignment 03 – Fluid form

Johan Wallhammar, Marieke van Dongeren


Concept: Spritzing concrete in several layers – like 3D-printing or spritzing cream on a cake

2 experiments:
– 1 on flat surface (Marieke)
– 1 on leaning surface (Johan)

Followed given recipe – with extra cement for a less fluid mix.

Four attempts were made at different times – so concrete was more cured:
– 1st attempt – directly when concrete was mixed
– 2nd attempt – 30 minutes after concrete was mixed
– 3rd attempt – 60 minutes after concrete was mixed
– 4th attempt – 80 minutes after concrete was mixed

Concrete mixture finished at 10.58.
– 1st attempt started at 11.03 – finished at 11.10
– 2nd attempt started at 11.30 – finished at 11.40
– 3rd attempt started at 12.00 – finished at 12.05
– 4th attempt started at 12.20 – finished at 12.25


1st attempt:
– heavy
– very hard to get concrete out of spritzer – we almost got cramps in our hands afterwards
– Mixture spritzed on flat surface was stable and could be built in several layers
– Mixture spritzed on leaning surface not as stable – fell over


2nd attempt:
– slightly less heavy, more fluid than 1st attempt.
– more smooth surface


3rd attempt:
– Perfect fluidity for spritzing –lighter
– more stable

4th attempt:
– slightly more fluid than 3rd attempt – less stable


Everything got wetter and more fluid as time passed – contrary to our expectations.
Johan had a bigger opening in his spritzer than Marieke. This might result in the different appearances of the tests.
The concrete was a lot blacker when we mixed it – after curing it got lighter.


Mix design:

mass (grams) parts percentage of cement
cement 1250 1
sand 2156 1.72 172.48%
fly ash 280 0.13 22.40%
silica 140 0.50 11.20%
water 420 3.00 33.60%
super plasticizer 18 0.04 1.44%
pigment 2.5 0.14 0.20%
total 4266.5 241.32%


Assignment 2 – group5

Group 5 – Maria Johansson, Marieke van Dongeren, Johan Wallhammar

3rd picture – from left to right:
Mix 1 – more sand: coarser, no flow
Mix 2 – more water: more wet, flows easily
Mix 3 (picture 2) – blue pigment: almost oily,we accidentally mixed the sand in before the pigment
Mix 4 – red pigment: nice and red
Mix 5 – black pigment: also oily – but mixed the right way (first cement+pigment – then sand)

We hit each mould against a steady surface to fill the moulds completely, and to get the air bubbles out. It did not work with the firstmix which was to stiff.

Both mix 3 (blue) and mix 5 (black) turned out slightly oily – as if the pigment did not quite mix with the cement.

We changed the proportions so that each mixture was 500 grams (the calculations by hand).


Fulgurite – Lightning rock

When lightning hits an area with lots of silica in the surface material such as sand, the material may fuse and create a lightning rock – known as a fulgurite. The tempereature inside lightning can go up to 30 000 Kelvins (29 700 degrees celsius), instantly melting and fusing  the sand.

Most often, the fulgurite is tube-shaped with a hollow interior. The insides of fulgurites are often glassy and smooth, due to the rapid cooling of the fulgurite after being hit by the lightning. If the fulgurite is not tube-shaped, it is called an exogenic fulgurite, which is when the material is thrown into the air during a lightning strike and then melted and fused.

Corn starch mould – gummies

(printscreen from video above) 

Corn starch molds are brittle moulds often used for making  gummy candy and wine gums. The wanted shape is stamped on a tray filled with corn starch, creating a mould. The hot candy mixture is poured into the mould. The candies are cooled for a few hours, after which the tray is tipped over, breaking the mould and separating the hardened candy from the corn starch. The corn starch is easily removed from the candy and can also be used many times again.