For my final assignment I wanted to cast a wall with possible places for mos to grow. By studying the growth of the mos on rocks I found out that the mos needed a concave place with a coarser structure. As I wanted the wall to be smooth I had to make inward curved areas with a more rough structure.
I used the casting technique of prepacked aggregate casting. Prepared with a flat box with thick paper forms witch I filled to half with sand and the other half with 4 mm aggregate. Then I casted with a cement slurry (1 part cement 3/4 parts water). After 30 minutes I took out the paper forms.
I did a test with the technic “prepacked aggregate concrete“.
First I build a little box which I divided in 25 parts with paper walls. I filled the little “rooms” as in the diagram below. When every “room” was filled with either sand or aggregate I carefully took out the paper walls and poured in the slurry. (1kg cement, 1,2 kg water). I hope the “slurry” will come down through the aggregate.
The result wasn’t so good. I think it depends on the fluidity of the slurry.
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.
Our group chose the topics hydrostatic pressure and mixed material.
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.
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.
Concept: Spritzing concrete in several layers – like 3D-printing or spritzing cream on a cake
– 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
– 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
– slightly less heavy, more fluid than 1st attempt.
– more smooth surface
– Perfect fluidity for spritzing –lighter
– more stable
– 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.
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).
This research was fostered by an interest in the formation process of diatoms and radiolaria, by Gabriel Sanchiz, Architectural Association, London, 2005-06.
Diatoms are unicellular or colonial algae and radiolaria belong to the order of marine planktonic protozoans.
The cast was made between two layers of rubber sheets, supported by a back-panel with an inflatable formwork.The result is a double-curvature cast. ”It can absorb thermal energy and release it to the airflow enabled by the porosity and the double-curvature can be utilised for exposure or self-shading.” (Gabriel Sanchiz)
I find this cast interesting because of Sanchiz´s ingenuity of finding a way to create a form with special qualities inspired from nature.