Since the invention of modern cement in the mid-nineteenth century, the excavation of stone and its redistribution in concrete form all around the world has been conducted on such an enormous scale that it is perhaps the clearest marker of human intervention on and below the surface of the earth. (Plant 2015: 8)

based on data in Krausmann et al. 2018 

The main ingredients of concrete, besides water, are the so-called construction minerals —limestone (for cement production) and sand and gravel or crushed rock (as aggregates). Their extraction has significant consequences for the biodiversity of the ecosystems concerned. The first ever global evaluation of this impact shows that about half the species that are endangered through construction mining relate to rock quarrying and the other half to sand and gravel extraction (Torres et al. 2022). Overall, the research group around Aurora Torres found that 1281 species were endangered or threatened by extinction (Torres et al. 2022).

Taxonomic group and habitat in relation to mining type for species impacted by construction mining. The width of each box is proportional to the number of species and intraspecific taxa included per group, mining type, and habitat type, while the colours denote mining types. Groups are sorted by the proportion of records for each mining type.

Icon credit: http://phylopic.org. Icon attributions licensed under CC BY-SA 3.0: fern by Olegivvit; dragonfly and scorpion by Gareth Monger; dolphin by Chris Huh; crab by Hans Hillewaert (vectorised by T. Michael Keesey); and millipede by Ralf Janssen, Nikola-Michael Prpic, and Wim G. M. Damen (vectorised by T. Michael Keesey).

In her philosophical supervision of the GC Conference, Susanne Witzgall, referring to Deleuze and Guattari, explained that the original ingredients of concrete lose many of their inherent singularities and ‘variable intensive effects’ (Witzgall 2022). As examples, we can name limestone, which acts as a water reservoir, and sand, which acts as a water filter. In the context of ‘New Materialism’, sand as a non-human entity can be seen as having agency and being capable of affecting and being affected by its environment. Depending on the way in which it is used, sand can be seen as having different potentials, capacities, and effects; when it is immobilised within concrete in a process of liquid petrification, its full potential cannot be achieved.

In this project, we have mainly focused on the extraction of limestone, but Christoph Weber completed a project for the Austrian Water Biennale about the historical manual sand and gravel extraction from the river Feistritz in 2017 (Weber 2017) and Nikolaus Eckhard manually extracted sand and gravel from the river Danube for his work Geschiebe in Form gehalten (2021; see the section ‘Concrete Times’).

In the installation Touch Fragments (2022), Christoph Weber tells the story of a transformation within the cycle from calcination to carbonatation — from the extraction of limestone to the building of concrete pillars for highway bridges and the ultimate consequence of the biosphere being trapped between the lithosphere and technosphere.¹ Using a newly developed photographic technique that involves moulding real-size impressions of surfaces with translucent mould-making material, then contact printing the results to analogue black-and-white photographic paper, Weber refers to human intervention via a methodology of sculptural touch. ‘He explores haunted and spacetime-mattering landscapes, as explored by Karen Barad: “Touch is never pure or innocent. It is inseparable from the field of differential relations that constitute it”’ (Derrien 2022; Barad 2012). The pictorial representations of human touch — the drilling holes in the limestone quarry, the surface of the broken limestone mountain, as well as the imprint of the concrete formwork in the highway pillars — are combined with Weber’s method of sculptural touching, which involves photographically recording air bubbles of the translucent mould material and particles of the original material. In this way, the artist reflects on his own role and use of human touch, visualising the merged character of original (extractivist) and secondary (artistic) interaction. This aspect hints at an important argument in the concluding section (‘Dissolution’) — namely, the fact that this research is directed not only against the concrete industry, as a welcome antagonist, but also against the parts of ourselves that are content with the comfort zones we have been growing up in.

The same imprints of technospheric extraction and petrification have been used to cast beeswax sculptures of average human size, where the fronts and backs bear the imprints of concrete pillars and the sides are marked by traces of extraction. There are two reasons for the difference in size — first, this reflects the typical size relation between humans and their architectural shells; and second, it emphasises a shrinking or squeezing of the biosphere, symbolising the technospheric pressure to which it is exposed. Furthermore, the choice to present beeswax as a human-sized sculpture relates to a question that scientists have posed in their assessments of anthropogenic mass and biomass: are humans part of the technosphere or of the biosphere?

The production of modern cement, including roasting limestone with clay minerals at 1450°C, is a highly energy-intensive and emission-intensive process, which results in the so-called process emissions of CO₂. The heating of limestone (calcium carbonate or CaCO₃) releases carbon dioxide (CO₂) from the long-term carbon cycle to the short-term carbon cycle, at a ratio of ~40% CO₂ emissions from the heating itself and ~60% from the release process.² Cement factories and scientists alike are trying to reduce both heating emissions, by using alternative energies, and process emissions, by altering the composition of the roasted minerals (Scrivener et al. 2018). Nevertheless, 2050 roadmaps have to rely heavily on carbon capture technologies, since process emissions are an inevitable part of cement production. An estimate of the expected consumption of concrete in the near future will be presented in the final chapter.

Regarding the question of global responsibility for cement’s environmental impacts, two common patterns of deflecting blame can be observed. First, the tendency of countries in the Global North to blame China for its overall high CO₂ emissions, while ignoring their own high per capita emissions, especially in the second half of the twentieth century. In fact, in Austria, these emissions are still high compared with other industrial nations. Second, in the case of Austria, it is argued that the percentage of CO₂ emissions from the overall greenhouse gas emissions relating to cement production is somewhat lower than the global value (3.1% in Austria compared to 4.5% globally) (Beton Dialog Österreich 2021). This, however, is just another way of saying that many other emissions-intensive sectors and industries are at play, since the per capita emissions for cement are high.

Source: Richie et al. (2023), based on the Global Carbon Project (2022).

Source: Richie et al. (2023), based on the Global Carbon Project (2022).

For his work sechs komma vier (2021), Christoph Weber researched how much cement could be produced per kilogram of burst limestone. Next, he chose a freshly burst chunk of limestone weighing approximately 200 kg, quarried in the Mannersdorf cement factory. The plan was to make as many concrete copies of this piece of limestone until the amount of cement in all the copies matched the amount the industry would have obtained from the original piece. He then calculated how many copies he could produce with his typical concrete mix (cement, sand, gravel, and water), which resulted in the number 6.4. He produced the mould, deciding to separate its two halves horizontally, since the seventh cast would need to represent 0.4, which is less than a half. In a conversation with the artist, Elisabeth Fiedler, the curator and art historian of Museum Joanneum, mentioned that he was inventing the sculptural representation of the decimal point, so he decided to emphasise the typical casting process of two halves, by clearly showing the production seams.

An important aspect of this work lies in the finite character of the multiplication. During the production of the seventh copy, Weber metaphorically ran out of cement (‘metaphorically’, because the original limestone piece was never turned into cement). As such, the sculpture alludes to the fact that humankind will have to find a way of dealing with planetary limits. We simply cannot go on with the logic of the infinite multiplication of the growth paradigm.

As of 2020, global human-made mass has surpassed all living biomass (Elhacham et al. 2020: 1). The cause of this growth has been modernism’s promise of improvement in four key areas: ‘Living, working, recreation and circulation’ are defined as ‘the key-terms of town planning’ in the Charter of Athens of 1933 (Curtis 1986: 173). Today, concrete, ‘the most abundant novel rock’ (Waters & Zalasiewicz 2018: 75), can be considered a signal of the Anthropocene. The material’s yearly growth in abundance (27 billion tonnes in 2017; 37 billion tonnes in 2023) is around twice the river sediment flux reaching the oceans (Waters & Zalasiewicz 2018: 83).

Redrawn after and licensed by Elhacham et al. (2020); reproduced with permission from SNCSC.

To grasp the enormous abundance of the accumulated concrete on Earth during our GC Conference, we calculated the average global concrete consumption as roughly 12 kg per capita per day, by assuming current global production of 4.1 billion tonnes of cement, which corresponds to around 34.7 billion tonnes of concrete for 2021 (Garside 2022). Every participant cast a small slab with a size of DIN A4 and a height of about 10 cm, corresponding to two packs of printer paper or 12 kg of concrete. After four hours of curing time, at the moment when the cement’s reaction started to fire and the concrete’s consistency was similar to clay, everyone uncast their slabs and threw them away in a cathartic manner.

Why is the accumulation of concrete such a problem? The industry claims that it is just creating future stock for urban mining (Beton Dialog Österreich 2021), which will be welcome when Earth has run out of sand.³ It also claims that a real circular economy is not yet possible, because concrete’s long service life hinders the reflux of enough material, and that the concrete in landfills is inert, behaving like a new kind of mountain and just waiting for future generations to use it.⁴ First, it seems highly unlikely that steel-reinforced concrete waste is really inert; and second, this does not account for illegal dumping, where concrete waste can mix with other kinds of waste, making its future recycling less probable. It is, however, important to acknowledge that Austria is using more than 90% of its construction waste, mostly as downcycled filling underneath new roads. Globally, that figure ranges from less than 1% in Brazil to around 10% in China and 90% in Japan (Gross 2019).

As stated by Fridolin Krausmann in the slide below, concrete recycling is practically non-existent. First, concrete rubble can only be downcycled to new aggregate, because it is necessary to add fresh cement and water for a new mix. Second, the re-use of built concrete elements, such as whole beams, has not yet been implemented in building practices.

Image: Copyright Jim Bain and licensed for reuse under CC BY-SA 2.0. Graphic: Hirokazu et al. (2005); copyright 2005 Japan Concrete Institute.

Bind (2022) was made for Via Detour, an exhibition at a treehouse hotel close to Kassel and a parallel event to Documenta 15. As the hotel’s owner also runs a recycling company (for misprinted labels), Christoph Weber asked him to obtain some concrete rubble from a local landfill. For Bind, he drilled 20 mm holes into a large chunk, to break it into smaller pieces, then stuck these into soft casts of beeswax, colophony, paraffin, and wood tar. The wax cubes are a representation of the biosphere, with the wood tar adding a typical sculptor’s wax mixture, to reflect a site in the middle of the woods. The work is a reflection of the biosphere’s tolerance as well as the tendency of humans — or rather capitalist societies — to take the biosphere for granted and consider it capable of absorbing human waste.

Confronted with the fact that concrete is responsible for the sealing of soils, the Austrian cement industry deflects the blame onto asphalt (Beton Dialog Österreich 2021). However, roads often have a cementitious base underneath the top layer, so concrete often plays a crucial role in their construction. The second commonly used argument against concrete being responsible for the sealing of soils is that it is actually enabling architecture’s vertical design (hence avoiding horizontal design and the greater sealing of soils), but this ostensibly positive feature is also playing a key role in creating overheated cities, so here again concrete cannot be absolved of its complicity.

The sculpture Furche (2021; Furrow) resulted from the collective efforts of fifteen people who were led by Nikolaus Eckhard as part of the Viennese educational project ‘Welt Teller Feld’.⁵ The artist and the participants reflected, through their manual work, on the efforts of modifying and sealing soil, as well as the ambiguities bound up with ground consumption.

The ‘Welt Teller Feld’, a project showcasing how much ground an average person in Austria consumes via their food choices, offered a fitting platform for exploring the reduction of such space through a direct and provocative act of sealing.

The participants in Furche manually pulled a plough across a field, a straight line breaking through the first layer of soil. This action formed a physical understanding of soil and its plasticity, while also opening up a connection with the universe of underground life: bugs running, larvae wiggling, ants digging, and roots stretching. Next to the field, concrete was mixed — and, in a collective act, it was then poured into the fresh furrow, sealing it to stillness. During the curing, the concrete rested, as a grey scar of modernity on the fertile land. Hours later, the hardened object was excavated and freed from the soil — the soil also being freed from it — before being buried in a vertical position up to half its length. The object changed its status, from sealed soil to stele, inscribed with the memory of its making: on one side, the marks of the plough’s blade, imprints of plants, shells, rough earth, and people’s sweat; on the other side, the sleek promise of modern living.

In Austria, an area of 15–21 km² is sealed every year (Umweltbundesamt 2022). The sealing of soils implies not only the inability of the ground to absorb water and prevent floods — a problem the industry claims to have solved, by using ‘drainage concrete’ in so-called swamp cities — but also the irrevocable killing of all organisms living in the soil. It therefore affects not only biodiversity and the extinction of species but also global food production, by making the soil infertile for potential farming, even after the removal of the sealing (Tobias et al. 2018).⁶

As displayed in the first slide of this chapter, the speed at which global anthropogenic material stocks accumulate is almost identical to increases in GDP, which was first introduced in the 1930s, as a response to the Great Depression. In 1960, it was adopted by the OECD, which gives the highest sustainable rate of economic growth as its top goal, indefinitely and for its own sake (Hickel 2020: ch. 1.2.4., par. 7, quoting Schmelzer 2016). ‘The idea spread like wildfire. During the Cold War, the grand competition between the West and the USSR came to be adjudicated largely by rates of growth. Which system could grow GDP the fastest?’ (Hickel 2021: ch. 1.2.4., par. 7). The economic paradigm of Growthism started. (Hickel 2021: ch. 1.2.4., par. 7).

Anselm Jappe describes a ‘passionate liaison between capitalist modernity and concrete’ (Jappe 2020a) and labels the material as capitalism’s weapon of mass construction (Jappe 2020b). In a Marxist line of thought, he explains the accumulation of capital as the accumulation of quantities of value given by abstract labour. Jappe continues:

Marx speaks of a ‘jelly’ to characterise this amorphous mass of abstract labour. But what corresponds better to this ‘jelly’ in material terms than certain materials such as plastic or concrete? Artificial, always the same, unrelated to its surroundings, capable of taking any form without having one of its own: concrete is perfect for concretising and materialising the fundamental and immaterial abstraction that dominates modern society […] We can use a little play on words to say that concrete is the concrete side of capitalist abstraction. (Jappe 2021)⁸

This ever-growing ‘jelly’ of concrete has cured on the construction sites of modern urban society’s housing and infrastructures. Matthias Schmelzer elaborates:

Urban geographers have documented what is called a ‘growth coalition’ or ‘growth machine’ of elites (primarily developers and politicians) who seek to spur and manage urban growth for the sole purpose of profit, functioning as a kind of ‘real estate state’. (Schmelzer et al. 2022: ch. 3.4.5 § 1)

He also reveals that: ‘Today, roughly 60 percent of the world’s capital is invested in real estate’ (Schmelzer et al. 2022: ch. 3.4.5 § 1, quoting Stein 2019).

If society’s focus on GDP does not change, there is little reason to expect the growth of anthropogenic mass to slow down:

The transition to sustainable levels of resource use will probably require adopting transformative post-growth and degrowth approaches, including abandoning GDP growth as a goal, reducing inequality, and organising the economy around human needs, while scaling down unnecessary commodity production. (Hickel et al. 2022: e347, quoting Kallis et al. 2018 and European Environment Agency 2021)

Concepts of housing for degrowth are currently being developed and vividly discussed by a growing number of researchers and activists (Nelson & Schneider 2019).

Quoting a study by Helmut Haberl et al. (2019), Matthias Schmelzer presented a slide about concrete’s connection to the Social Progress Index, suggesting that around 50 tonnes of accumulated concrete per capita might be sufficient for a good life. Following this argument, production above this per capita level could be considered as unnecessary commodity production.

Licensed by Haberl et al. (2019); reproduced with permission from SNCSC.