limestone

Palliser Limestone Formation: at the base of Heart Mountain, next to the Canadian Pacific Railway at Exshaw, Alberta, about 900 000 tonnes are quarried annually, sliced off the hillside like carving a block of butter. Natural gas supplies the energy to turn it into cement powder.

Portland cement: limestone is fired at 1450C, a process which frees CO2 from calcium carbonate to form calcium oxide, or quicklime. Gypsum is added, and depending on geography, a number of other additives such as fly ash, blast furnace slag, silica fume, various clinkers, sometimes metakaolin (to make it very white).

Strangely, cements are considered natural materials, I suppose because they are made of 'natural' mined minerals, such as limestone and bauxite.  Now here is an interesting one: calcium sulfoaluminate low-energy cements require lower kiln temperatures, less limestone, thus less fuel consumption, less CO2 emissions, but 'significantly higher' SO2 emissions, which if I recall leads to acid rain.

Green cements using waste containing calcium, silica, alumni or iron, can replace clay, shale and limestone in the kiln, and other waste material can be used as fuel rather than coal or natural gas.  It isn't clear if this produces cement that can be used for structural concrete.

Novacem, a research facility in the UK, has developed a magnesium silicate-based strong cement which absorbs CO2 as it hardens, making it carbon negative.  Geologically speaking, limestone is very common throughout the world, supposedly so are magnesium silicates.  Although one can develop a new carbon negative cement, getting it to replace existing, long-standing industrial processes is more difficult.  Magnesium silicate is more commonly known as talc [Persian تالک] as in talcum powder: soft metamorphic rock, the main ingredient of soapstone.

But. but. and this is what I can't find, does the concrete made from all these different cements feel and look different from the energy consumptive Portland cement?

béton brut

 The columns under the Queen Elizabeth Hall, South Bank, London. 1967 Hubert Bennett, GLC, architect

This is the underpinning of the Queen Elizabeth Hall on the South Bank, London, built in 1967.  The South Bank was a massive cultural centre built after WWII in Lambeth. It epitomises what came to be known in Britain as Brutalism, the term derived from béton brut, or raw concrete, but with all the unfortunate overtones of brutal thuggery.

The image above shows precisely what annoyed Fisac about rough board formwork: it looked more like carpentry than heavy, plastic concrete.  That is all true in terms of material, but in terms of construction and the fabrication of buildings there is something quite wonderful about the fragility of wooden boards, carpentered together because they are needed by the big brute to make form.  The boards leave their ghostly presence behind, forever imprinted on the obduracy of concrete.  The whole building is built twice: once in wood, then again in concrete; the wood is a mould, the concrete the sculptor's material. 

We rarely see concrete formed this way for large projects anymore, unless for bridge piers and earthworks, and of course foundations; the concrete mostly visible in buildings is pre-cast, all the slots, channels, fixing points and surfaces carefully designed and controlled off-site.  This gives the surfaces the ability to be decorative, less forceful than rough poured concrete.  I really dislike precast concrete.  There is so much of it.

Matsys: P_Wall

Matsys, P_Wall. Banvard Gallery, Knowlton School of Architecture, Ohio State University, Columbus, Ohio. 
15′ x 9′ x 1′, 200

Matsys, the studio of Andrew Kudless, investigates architecture as a material 'body' with its own behaviours, forms and processes of integration.  One of the most photogenic projects is P_Wall, which uses plaster and nylon fabric.  Lest one think this is a random or organic form, it actually derives from pattern analysis. From Matsys's website: 'Starting from an image, a cloud of points is generated based on the image’s grayscale values. These points are then used to mark the positions of dowels which constrain the elasticity in the fabric formwork. Plaster is then poured into the mould and the fabric expands under the weight of the plaster. The resultant plaster tile has a certain resonance with the body as it sags, expands, and stretches in its own relationship with gravity and structure. Assembled into a larger surface, a pattern emerges between the initial image’s grayscale tones and the shadows produced by the wall.'

I love the way we shift from the poetry of 'a cloud of points' to the clunkiness of dowels; such is the process of making architecture.  However, another phrase, 'the self-organization of material under force' is a powerful concept.

Matsys, studio: P-Wall tiles drying, 2009.In 2009 San Francisco Museum of Modern Art commissioned a 45' x 12' P_Wall for the exhibition Sensate: Bodies and Design.  Because this kind of hard surfaced building material – they are essentially tiles, to be attached to walls – is unlike any other we have seen, the form calls up any number of metaphoric readings.  Henry Urbach, the curator of Sensate' in his curatorial essay went directly to the parallels with the human body, as if we were also stretchy sacs pinned together, bulging with the weight of too much weight.  

A detail shown on the Matsys documentation of this SFMOMO installation is innocently captioned, 'Detail of a crease.  Notice the surface texture left by the fabric form.'  Well, yes, we can see the delicate texture of the original knit fabric, but we can also see Weston's photographs of vegetables and nudes  — clearly and purposefully sensual.

Edward Weston, Pepper, 1930; Nude, 1927. Edward Weston negatives, Cole Weston prints.Matsys, P_Wall, 2009. Detail of a crease. Notice the surface texture left by the fabric form.

Concrete canvas

Flame test on an emergency shelter made from a Concrete Canvas kit.

Right.  Concrete.  Here is something called Concrete Canvas, a double layer of tightly knit fabric with cement powder between.  It is flexible, light (5, 8 and 13mm thick), is put in place and then hosed down, forming a thin concrete skin.

It appears to be deployed all over the world for emergency shelters, ditches and water redirection, slope stabilisation and concrete repairs.  Its military applications include reinforcing sandbags and bastions and laying down emergency hard surfaces.  It comes in rolls; it seems magical. The emergency shelters could use some design attention.

They have a kit which includes an inflatable liner attached to a front gable door panel, which is inflated, draped with concrete canvas, watered and is ready in 24 hours.  Other openings can be cut in after it is rigid.  The strength is such that it can then be bermed.

I chose the image above from a vast array on the Concrete Canvas website because it is dramatic, but also shows the texture of the surface.  Unfortunately the inside is lined with the plastic from the inflatable – shiny, maybe sweaty.  Emergency shelter is the operative term. It would be very interesting to see just how far these shells could be adapted for permanent use. 

Miguel Fisac: encofrado flexible

Miguel Fisac's own studio in Madrid: concrete poured into flexible formwork, 1971.

Miguel Fisac, 1913-2006, patented and used an idea in the late 1960s for polythene and a rigid frame as formwork for concrete, feeling that using wooden boards as shuttering was 'an incorrect texture' with its references to carpentry and organic and familiar wood grain.  Concrete on the other hand was 'a material that was poured in a liquid state, more closely approximating a stream of volcanic lava'. [this from the Fundacion Miguel Fisac and the section 'Epidermal Years']

Diederik Veenendaal, writing about Fisac for a dissertation at ETH Zürich, refers to Paul Galabru's 1964 book Obras de fábrica y metálicas and 'encofrado flexible' (flexible formwork), from which he speculates that Fisac, had he owned this book, would have found it an influence. 

Fisac himself is an influence, clearly in the work of Mark West, who began to use flexible formwork in 1986.  Trust that this kind of material sensuality came from Latin culture. 

Rachel Whiteread

Rachel Whiteread. Parts 1-4 of House Study (Grove Road) 1992. Courtesy the artist and Gagosian, London © Rachel Whiteread. Correction fluid, pencil and water-colour on colour photocopy, 29.5x42cmThere is an absolutely wonderful interview/discussion between Rachel Whiteread and Bice Curiger, the co-founder and editor of Parkeet.  Rachel Whiteread has an exhibition of drawings at Tate Britain until mid January 2011.  The discussion looks at the things in her studio that she has collected, including a plaster cast of Peter Sellers' nose, it talks about what her drawings do, it revisits the Grove Road project.  It is delightful.