Another successful experiment in flexible membrane concrete casting is the KnitCandela project by the Block Research Group, which created a five tonne concrete shell with an area of 50 square metres using fabric formwork.The formwork was comprised of flexible cable nets and a large piece of 3D-knitted shuttering. One incredibly impressive feature of this sculpture is the reduction in concrete mass that was enabled by the team’s use of fabric formwork, which, in
discussed with the fabric formed concrete cylinders, and kept many comparable control variables. I noted, however, that there were also multiple differences between the two tests. I found it very helpful that the testing was run differently between this and the concrete cylinder experiment that I analysed earlier. The independent variable changed from the max load measured (in the concrete cylinder experiment) to the mass of concrete needed to support a set mass (in the prismatic beam experiment).This allowed me to see the benefit from two different angles, and it makes the conclusions I am drawing about fabric formed concrete being stronger, more solid, and better based. In both, the same conclusion was reached: fabric formwork is noticeably better at loadbearing, even with a smaller mass.This conclusion was reached through the testing of four different beams, all of which were designed to have the same 8 metre span, but had more support at different points along each beam. These designs were scaled down by 50% and then loads were placed on each beam to see how much they could carry before reaching breaking point. Comparing Beam 1 and Beam 4 gives the most easily identifiable differences. Beam 1 had an average concrete strength of 42N/mm squared and upheld a maximum load of 114kN, while Beam 4 upheld a maximum load of 133kN, with an average concrete strength of only 33N/mm squared (Figure 2). Beam 1 was a prismatic beam with constant external proportions, whereas Beam 4 had points of maximum and minimum diameter, and tapered in and out to meet these points.Therefore, it brings the suggestion that an irregularly shaped, non-prismatic beam is often much better at load bearing when optimised to work around the areas of highest and lowest stress.The first experiment with the beams suggested a concrete material saving of roughly 35% by using a more efficient design created by fabric formwork, where the mass of concrete is spread out with the high and low stress points in mind.After further testing and additional experiments, this value was raised to 40%, which is an incredible amount of concrete saved (Orr et al.,2011). In my opinion, this is the clearest demonstration of the practical and functional benefits of fabric formwork. Being able to withstand the same load with such a significant reduction in concrete mass attests highly to just how much stronger fabric formwork is than regularly formed concrete. If designed efficiently, we could reduce concrete necessity considerably – a benefit I would also associate with the others discussed in this essay: cost and sustainability.The less concrete you need, the less you have to buy, and therefore, the less it costs. Similarly, the less concrete you need, the less you have to make and, therefore, the less emissions produced.This cross-sectional benefit is why I believe fabric formwork could have a measurable impact if implemented across the different areas of construction.
my opinion, would be possibly the most significant benefit of applying formwork
techniques if the reduction in concrete mass necessary was significant. I believe this would be especially beneficial because it links back to the sustainability benefits of fabric formwork as, if we can use less concrete, we can reduce the emissions produced. Of course, for this to hold any substance, the benefit must be proved first. While the concrete shell weighed five tonnes, it was able to be entirely held up by just 25kg of the knitted fabric and 30kg of the cable nets (Block, 2018), which means that a five tonne structure is capable of being supported by only 55 kilograms of formwork. I find this very promising for a future where concrete use needs to be limited as, if the structure was entirely concrete and needed to be held up by itself, it would require an enormous mass of more concrete (and an entirely different design incorporating support beams or pillars). I find this is best summarised by Mariana Popescu, who worked on the project and who explained the importance of KnitCandela as something that “demonstrates that complex concrete structures can be built at low economic and environmental cost through the strategic use of computational design and fabrication, combined with craftsmanship” (Popescu, Rippman, Mele and Block, 2020). In an aim to further explore the functional benefits brought by fabric forming concrete, I looked into the research run by the University of Bath, which ran an experiment in 2011 exploring the strength offered by fabric formed concrete beams. I decided this was a trustworthy source as the research was conducted by a well-respected university, whom I know, through my own research, have very up-to-date facilities, and so would be able to accurately measure their test results and carry out a well-controlled experiment. I hoped that their research would back my previous arguments about fabric formed concrete faring better as regards to loadbearing, and so condensed my focus on the very long report into just their sections on loadbearing and strength.The university found that a concrete beam with “optimised” formwork could have equal strength to a beam that was the same cross-sectional area the whole way across (also known as a prismatic beam), while using up to 40% less concrete, which is clearly beneficial.This experiment was similar to the first example I
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