by Gavin Lucas
Concrete is arguably a very modern substance – even if its usage is known from antiquity, the material has very modern connotations. Indeed, concrete architecture is perhaps synonymous with modern architecture. In the English language, reference to concrete as a substance only entered the vernacular in the nineteenth century. But concrete is not just a modern material – it is also anything which is solid, real. This other, philosophical meaning of the word goes back at least to the fifteenth century and its juxtaposition with the word used as a building material is mostly a quirk of the English language – but a provocative one nonetheless in associating a particular material with what is most real or solid. In other languages however, this association is lost –in German and French, the word for concrete is beton or béton respectively, which has a rather different etymological meaning: glue or binding agent – cement. In Icelandic it is similar – steypustein (cement stone). Indeed both words – concrete and beton – derive from the latin, concretus (hardened, solidified) and bitumen (mineral pitch, coal tar) and highlight some of its most salient properties: a liquid which hardens and also a substance which binds or holds together.
Now we come to the point of this etymological excursus. Concrete is not a fixed substance or material, so much as it is a process – a material which changes its nature over time. Already, the connotations of solidity are starting to drip. Liquid modernity. Indeed, concrete is notorious for being a versatile material, able to mimic other substances (even if only skin deep – but is there any other way?), to imprint the memory of absent materials, whether this is the grain of the wood used in the formwork, or the more eerie, inverted inside of spaces as seen in Rachel Whiteread’s casts like House or Nameless Library.
Adrian Forty, in his wonderfully rich study on concrete, highlights the indexical quality of concrete – something which preserves the traces of the construction process through the ridges and patterns left on surfaces by the formwork. Liquid turned to stone. Indeed, in considering the actual work involved in making concrete structures, Forty has also showed us how un-modern concrete construction actually is; aside from the use of pre-cast panels, most concrete buildings rely on traditional crafts, mainly woodworking, to construct the shuttering or formwork on site, and on familiar processes such as mixing, stirring and pouring. However modern the finished product, the work involved in making concrete buildings draws heavily on traditional practices. The concrete farmhouses that dot the landscape of Iceland and replaced the turf buildings may look more modern, but their construction relied on many traditional skills, simply put to new uses. Indeed, many of these concrete structures are hybrids, using turf infill in a cavity between concrete faces as a form of insulation – just as they used to do with undressed, stone faced buildings.
If concrete is a fluid which takes the inverted form of others, like a bodysnatcher, it is also a substance which binds or holds things together. Concrete is typically composed of three elements: cement, water and aggregate. The cement is manufactured in centralized industries and largely composed of clay and chalk, while the water and aggregate tends to be local.
Mixing in the right proportions is essential to the durability of the hardened product, but so is the use of the right materials. Cement production has become highly regulated, but the use of poor aggregate or sea water can result in very unstable concrete. Indeed, the solidity of concrete is not just undermined by the fact that it is a liquid turned solid, but that it is a solid which can also revert to liquid or crumbs. A whole science of concrete pathologies has been developed to examine how concrete decays. A common problem is alkali-aggregate reaction (AAR) or concrete cancer as it sometimes called, which is when the alkaline nature of the cement reacts with carbonates (ACR) or more commonly silica (ASR) in aggregates to produce a silica gel, which as every archaeologist knows, absorbs moisture. In concrete, this causes fissures and cracks as the gel expands like a network of veins just visible beneath the skin, or a weeping wound when carbonates crystallize on the surface, known as efflorescence. This process of decay is almost the inverse of what occurs with most buildings materials, which decay from the outside in, whereas AAR is a decay working from the inside out. A pathology where concrete’s own material properties are turned against itself.
Concrete is a complex substance. We may think it paradigmatically modern but it subverts the very opposition of modernity and tradition. We may think it is a solid, enduring substance but is born a fluid and can die as fluids grow and seep from its very core. Concrete is not all it seems.
Forty, A. 2012. Concrete and Culture. A Material History. Reaktion Books
Macdonald. S. (ed.) 2003. Concrete Building Pathology. Blackwell Science.
Hannesson, G. (1943) Húsagerð á Íslandi. In G. Finnbogason (ed.) Iðnsaga Íslands (vol.I), Iðnaðarmannafélagið.
Unless noted, all photographs by Gavin Lucas/Elín Hreiðatsdóttir.