ESALA making concrete more sustainable
The Edinburgh School of Architecture and Landscape Architecture (ESALA) has been encouraging students to experiment with concrete in order to make it more sustainable.
Remo Pedreschi was interviewed by Aida De Heras Olivares and James Tooze, MSc in Science Communication students on placement with the Department for Social Responsibility & Sustainability.
Read their blog about carrying out research for Action for the Climate.
What is the first thing you think of when someone mentions concrete? Brutal? Harsh? Boring? Meet a researcher in the University of Edinburgh who is looking to change the way we use concrete and challenge these stereotypes, which can also help to lessen the carbon footprint of concrete construction.
Remo Pedreschi is a Professor of Architectural Technology within the Edinburgh School of Architecture & Landscape Architecture (ESALA). Professor Pedreschi is an engineer and joined the School of Architecture after a period in the construction industry. He works with a number of companies on the development of materials and systems.
“One of the things that’s always interesting is ...what’s the context in which you work? (After studying as an engineer) I was used to working in an empirical, scientific way. Being in the School of Architecture, one thinks ‘we should look at things in a different way, we’re more design-orientated here and we’re orientated towards creative applications of materials’. However we never lose sight of the underlying science of materials. So that informs what we do.”.
Flexible fabric formworks
Professor Pedreschi’s research interests lie with how using innovative materials can help to shape design, and how these novel design processes can be used to create new forms of construction and architectural expression. These interests have currently been focussing on using a wide range of fabrics and textiles to cast concrete, known as flexible formworks. In a far cry from using traditional steel or timber formworks, flexible fabric formworks structures, apply a ‘soft logic’ that can have multiple benefits over their expensive and rigid rivals.
“With flexible formwork we can eliminate most of all of this bracing and simply allow the fabric to deform, but by controlling the deformation we control the geometry. By looking carefully at where one needs to be accurate, we can take advantage of having the flexible formwork to produce much more efficient formwork systems, much more effective and interesting geometries, and we have a better control over the texture and finish of the surface of the concrete.”
As Professor Pedreschi continued to explain, the flexibility of this process is not just related to the physical make-up of the fabrics used, but also the endless possibilities of the shapes and designs you can create using fabrics. Then feeling of the ‘harshness’ of concrete is currently created by the way it is shaped and formed, Professor Pedreschi included. By sewing fabrics into shapes containing holes, extra ‘arms’ or even more complex stitching patterns, concrete can take forms previously unimaginable that would otherwise require expensive and complex steel formworks.
“Conventionally concrete in its liquid form is placed into a wooden box, that wooden box is rigid and designed to remain rigid, and not allow any leakage, it’s about constraining it (concrete). We adopt a process where we use formworks ,that are flexible. Using fabrics seems somewhat counterintuitive to people that construct buildings conventionally”.
Although there have been examples of casting concrete into flexible formwork as far back as the late 19th century, the recent resurgence in the technology has shown the full potential for the future of this technology.
“Our studies in the last ten or twelve years have really convinced us that for many applications it (using flexible fabric formwork) is often appropriate and there are a lot of additional benefits that one can get. We see benefits in terms of geometry, in terms of simplicity of constructions, in terms of quality of finish; very important in the perception of concrete as a material in the environment”.
The benefits of this technology are not only superficial, however. The use of fabric formwork techniques has helped to provide a great insight into the forces experienced by concrete. Allowing concrete to flow inside a piece of fabric formwork helps to aid our understanding of the natural behaviour of concrete when it is subject to fewer constraints than traditional rigid formwork.
“The fabric, actually, has a kind of intelligence - it responds to the pressure that it’s dealing with rather than try to resist and hold everything. Concrete flows while it is wet and the fabric deforms into the most efficient shape possible. This is analogous to Gaudi shaping the Sagrada Familia using suspended cables and weights. That is the optimum geometry for that particular series of loads, and as I said the fabric does this intuitively or naturally.”
“It then becomes an issue of how one controls that, of how one makes it do the things you want it to do. But instead of restraining everything universally you tend to find the points at which you need to control and you have a more nuanced understanding of the nature of the element by doing that. So we can produce very accurate pieces of concrete still using very flexible, lightweight materials and that’s inherently sustainable.”
The use of these fabric formworks can help to not only to improve the sustainability of concrete construction, but also allow for greater control over the shapes of concrete beams or columns for a fraction of the price. As the fabrics will be flexible, they still require fixed points to ensure they make the desired shape, but due to the fabric stretching into these ‘force-efficient’ shapes less reinforcement is required. The research conducted in the University has shown that as a result of using fabric formworks, curtailing the need for reinforcements from materials such as steel can reduce the carbon footprint of the concrete forming process by approximately 35%.
“We have studied, for example, the beam in some detail from more of an engineering point of view, where we could establish the (change in) carbon footprint.”
“We’re currently doing a series of studies looking at the effective shape of a column (the vertical element), trying to see how we can take advantage of changing the shape to increase the load the column can sustain. We have found that we can obtain quite significant increases in load by changing the shape from a cylindrical, prismatic column with constant diameter and shaping it to waist in the middle. This can provide substantial increases in load for the same amount of concrete.”
The research within the University has not only allowed for collaborations between the Edinburgh College of Art (ECA) and the School of Engineering, but has also provided a fantastic opportunity for many Masters and PhD students to get to grips with this novel technology.
“…we created a studio in the workshop and let the students design their own things. We guided it quite carefully. We decided that what we wanted to do was for them to be able to build something that they had conceived of at as big of a scale as possible and as effectively as possible, and to do this all in a maximum six weeks. And so we structured a programme very carefully to do this. The students, then, have to document and reflect very carefully on the process and picking up where they have possibly made mistakes, where there could be improvements, how they might see the technology expand.”
The future of flexible formwork
So what does the future hold for flexible concrete formworks?
Flexible fabric formwork is a disruptive technology that challenges the traditional paradigm. Some work by Professor Pedreschi and his team has already gained wide recognition, the University of Edinburgh provided 19 ‘tree root’ concrete panels for use during the Chelsea Flower Show, which helped the artist Paul Hensey win the prize for Most Creative Garden in 2009. The future does look promising for these technologies, but a change in attitude and conscience may be required.
“It can start off with the relatively slow growth by people who are really interested in using it... so it’s great for self-build, it’s great as a teaching vehicle - we’ve done a number of projects with schools. Potentially though, there are great opportunities for it to be used in more mainstream constructions, but it requires a shift of practice.”
“It’s a slow burner in some ways. We get a lot out of it just by the process of doing it, and our students learn a phenomenal amount about construction and materials, but we feel there’s still a way to go before it becomes adopted in the mainstream.”
MSc Material Practice
In the wake of this research, and in collaboration with other areas of the ECA, the University now offers a one year Masters programme in Material Practice. The MSc offers the opportunity for students to become accustomed to designing and casting materials from concrete, textiles, metal and glass, while enabling students to explore the boundaries of their understandings of the potential of these materials.