Final casts on display in the entrance of KTH School of Architecture between 28/4-5/5
Marieke van Dongeren
Pia Victoria Hocheneder
we wanted to cast a grid in concrete, since we did not manage to succeed in assignment 04. after the things we have learned by failing, we tried it in a bigger scale.
first tristan donated one of his t-shirts, which seemed to have a good stretchy fabric.
then we sewed the pattern where we wanted to have the holes. a self-built funnel helped to insert the concrete. we wanted to put up the fabric on a construction that the mass could flow down into the form by gravity.
after the casting we already saw some weak spots where we thought it will break, but the concrete is so hard that it still is one piece.
we have learned a lot by doing it again and by approaching us to the result we wanted to have. if we would do it again, we would probably change the shape a little bit, since aesthetically speaking we could still improve it. furthermore we would also sew the upper part, which we did not to be able to insert the funnel, but it would have worked with just one opening, too.
in addition, we also wanted to do another grid, where we tried if it might also work with thinner concrete. the casting method was quite ‘normal’, we made a mould out of cardboard. but we expected it to break, because we thought it will be too thin.
therefore we were surprised when we demoulded it, because it turned out well and it was very solid.
I decided to make a paper model to cast in sand using the adaptive formwork technique. I chose to use the digital site information from my studio project and make it in scale 1:500. The final model would then be approximately 70*50 cm. I used a type of 300 gram paper to cut each height level and the same type of paper for the 2mm height difference for every curve. The model was then assembled using tape.
For casting with every level in the correct height I cut out several mirrored sections from the site to support the paper model from the bottom of the bounding box. The thought was that I would use these sections to level the sand underneath the model to get everything in the right height. This didn’t turn out well because the sand didn’t hold to this grid of sections.
I therefore shaped the sand through pushing and shaking the sand underneath the paper model, this method was not precise, but it seemed to hold the shape of the model well enough. I used a very coarse aggregate to fill the model, to make sure that the concrete slurry would filter all the way to the bottom. The size of the aggregate was roughly 10mm. For the slurry I used 0,75 part of water for 1 part of cement, in total 7 kg of cement.
I think that the paper was to thin for the size of the model. It was to difficult to shape an area of 50*70 cm of sand underneath a model. The edges of the model was to thin, so it bended, also because the aggregate was so large that it didn’t shape the model from the inside. For the recipe for the slurry I think that I could have used less water since the aggregate was larger than in the previous assignment.
Inspired by the shapes of tree-growing shelf fungi I set out to do my own ones in concrete to use as ordinary shelves. Fungus-looking shapes were drawn on MDF boards and glued 90 degrees to each other, adding a stretchy t-shirt fabric to make up the front side. The fluid mix from assignment 4 was used, including the plasticizer to be able to have some working time before it would harden.
Two casting rounds were made, the first one with two smaller 15 cm wide prototypes. Plastic and fabric was tried for the front side, with fabric turning out as the winner with its more smooth look.
For the second round 3 shelves were made, one smaller 20cm wide variant with simple round edges and two considerably larger around 35-45 cm wide with wobbly edges.
The second round didn’t quite turn out as I wanted it to. The fabric I was using wasn’t strong enough for the massive amount of concrete and I had a hard time controlling the shape. I also failed filling the molds up with enough concrete to fill up all of the shape, as I realized when the concrete was already hardening. Also, the sheer weight of such big concrete objects would make them quite unsuitable for hanging on a wall.
A smaller sized mold with a stronger fabric stretched to its very limits would have made it easier and more stable to work with and easier to fill to the brim.
In the end I am most satisfied with my small shelf from the first round, and the cloudy white molds themselves were really the most beautiful things I have produced in this course.
My initial idea is to try to use concrete to copy this paper folding structure showing above. As a result I may get a shell-like concrete structure which is generated from the shape of the paper.
I choose the fabric form work to achieve this.
Using the sticks and strings to imitate the folding edges of the paper, and then cover it with the fabric to get the mold.
The recipe of the concrete is 1 cement, 0.5 water and 0.5 sand. The mixture is almost liquid like, which makes it easier to pour it evenly onto the fabric.
Due to the weight of the concrete, the wooden sticks bent to a curve.
At first I used 1kg of the mixture. But then I doubled it to make the structure bend over even more, As a result I got an approximately semi circle, which is a more reasonable shape for a shell structure.
Made a mistake when I went to check it about 24 hours later. I somehow moved it and the wooden sticks suddenly rebounded and teared my cast apart. But I managed to glue them together.
This is the final view of the cast. As the cast is the opposite to the mold. It is actually not a very strong structure. The position that is supposed to be beams are actually weak while the position of ceilings are too heavy. I think if I use the concrete as the mold and cast again then I can get a reasonable structure.
As a part of the course we had an assignment called flexible formwork. During this assignment we learned about the possiblity of casting concrete in fabric.
I was very intrigued by this assignment since this technique allowed for casting concrete with a very soft appearance. I liked how the concrete could be both permanent and hard and at the same time show great softness. It also allows for natural forces, such as gravety, to affect the casting.
From thinking of this I got the idea that concrete could mimic the softness of bodyparts. Since concrete makes the transformation from being a soft mix into a hard shape I wanted to take advantage of that it is possible to reveal impressions in the casts. And so I thought of what I could find out with this and I came to the conclusion that I wanted to make casts of bodyparts which are deformed by being pressed against something else. By these casts I want to expose the surface of the body which is otherwise hidden behind what it is compressed against.
Thinking more about this I realized that breasts are the perfect bodypart for showing this. The casts that I have made consists of breasts reavealing what they look like when being pressed against another bodypart. The casts show a frozen moment and might also tell an entire story.
For the casts I used the recipe which we recieved for the flexible formwork assignment. The rather loose mix made it possible for the casts to deform when pressed against something else but at the same time maintain its shape.
For the casting I used two layers of nylon stockings, fastened on a sheet of wood. By giving the stocking just a litle bit of shape the cast kind of shaped itself and the final result was therefore rather unpredictable. For me this was very important since I see this as an experimentation in deformation.