Introduction: Concrete and the City

A Gray Matter

"Those youngsters over there are on strike because they want to be allowed to retake their exams," explained one professor at Benin's largest university, the University of Abomey-Calavi. "They want to start a revolution but they know nothing about life. They do not even know the price of a bag of cement". In 2016, I had just arrived in Benin to begin three?years of field research in West Africa, and the social meaning of concrete was already becoming apparent. A few short weeks later, colleagues at the university asked me to contribute to a group gift for the retirement of an eminent professor: "We're offering him two tons of cement," they told me, "it's a mark of prestige and respect".

In West Africa, concrete - a mix of cement, sand, gravel, and water - is increasingly taking hold in physical landscapes, popular consciousness, and everyday conversations across the region. Concrete's presence is first of all physical: roads are lined with an infinite stream of cement warehouses and hardware stores where you can buy bags of cement and breeze blocks, as well as gravel, sand, reinforcing steel, and corrugated iron. Concrete is economically important: its price per ton is chalked up everyday on shop fronts, like prices on a stock exchange (Figure I.1). Concrete is also socially significant: it has come to symbolize success, wealth, and modernity. In the streets of the region's metropolises, lotteries promise prizes of plots of land and tons of cement (Figure I.2). In Lagos, a 12-year-old boy told me that he would like to become rich and famous, but he was unsure if the best way to realize his dreams was to become a Champions League footballer, like Samuel Eto'o, or a cement maker, like Aliko Dangote, the wealthiest African man in the world.

FIGURE I.1 Price of cement, Cotonou 2018.

Source: A. Choplin.

In this part of Africa, a sea of concrete is quickly swallowing up formerly verdant landscapes. The pervasive gray color of concrete is a reminder that cities are permanent building sites and that West African cities, in particular, are constantly under construction. Concrete is ubiquitous: both in the city centers where cranes build modern skyscrapers and in the distant suburbs where poor households incrementally construct their homes. Day and night, building seems to be the dominant activity. It is frenetical. On one plot of land, bags of cement wait, breeze blocks stand drying in the sun. On another plot, steel reinforcing bars point toward the sky, announcing the addition of another story to a growing building already reaching high into the sky. On yet another, men mix cement, water, gravel, and sand to give birth to concrete. The result is a cold and mineral landscape. Yet this landscape is also human and alive. Because behind this inert material, there is life: the lives of powerful decision-makers and lobbyists who have established their careers through concrete, as well as the lives of a handful of ultrarich and millions of poor residents. Everyone is linked to this 'stuff' of great banality. Concrete embodies the hopes and dreams of men and women seeking to shelter their loved ones, while it also allows the wealthy to exploit natural landscapes and resources - they dig holes to extract sand, gravel, and limestone to make the concrete needed to build luxurious high-rise towers. People are digging deep and building high, creating a new topography of West Africa's world of concrete - extraction, construction, distribution, destruction, and the flows of material in-between. Excavators, concrete mixers, trucks, cranes, and bulldozers: these are the machines of concrete cities which are merging into each other to create today's urban corridor in West Africa.

FIGURE I.2 Twelve plots and 150?tons of cement to be won, MTN lottery, Cotonou 2017.

Source: A. Choplin.

Age of Concrete

Age of Concrete

At that time, huts were transformed into villas in a glory of concrete, whereas with the annihilation of economic production came the reign of the city.

Patrick Chamoiseau (1992), Texaco.

In the novel Texaco, the Martinican novelist Patrick Chamoiseau (1992) recounts the saga of a poor Creole family in the titular shantytown of Texaco in Fort-de-France (Martinique). Chamoiseau divides the story into four periods which correspond to the various stages of the emergence of the shantytown: Age of Straw, Age of Crate Wood, Age of Asbestos, and Age of Concrete. The novel ends in the 1980s along with the Age of Concrete. But, if the story had continued, would Texaco have another material era after concrete? Forty?years later, it seems that the Age of Concrete has not ended but has instead relocated across the Atlantic - today, West Africa has arrived in its own age of concrete.

Archaeologists have summarized human trajectory in terms of material eras, like the Stone Age and the Bronze Age. And scientists have similarly named the planet's present geological era the Anthropocene. But could the world's material era also be defined today as the Concrete Age? How has concrete contributed to this new period of geologic time? As successive waves of concretization have concatenated over time, concrete has come to place a heavy carbon footprint on the contemporary world. Concrete was invented 150?years ago. Or "reinvented" to be more precise, as the material has multiple origins, all linked to the history of cement: at the beginning of the nineteenth century, the English clergyman James Parker invented "Roman cement," a fast-setting hydraulic lime. Following him, in 1824, Joseph Aspdin, a builder in Leeds in England, filed a new patent for a method of making a cement he coined "Portland cement." At the same time in France, Louis Vicat discovered in 1818 the principle of the hydraulicity of lime, the property of hardening with water, which would lead to the development of Portland cements in the 1860s. Since that time, the term Portland cement has referred to all hydraulic cements used to make concrete (Simonnet 2005; Courland 2011). One century later, in the 1920s, the Bauhaus School introduced concrete into construction as part of the rationalist and functionalist movements, which subsequently influenced architects like Auguste Perret and Le Corbusier (Forty 2012). Reinforced concrete underpinned the period of reconstruction and mass urbanization following the Second World War, and this turn toward concrete had the further effect of standardizing and simplifying an increasingly global construction industry. The historian Adrian Forty recalls that concrete was, at the time, associated with socialist and communist ideology and was therefore widely considered left-wing (Forty 2012: 150). During the 30?years of economic growth that followed the war, many considered concrete a noble and modern material. Le Corbusier - and the brutalist movement more generally - contributed to the glorification of concrete in the 1960s (Calder 2016), and today starchitects such as Rudy Ricciotti (2020) are advancing similar sentiments. Concrete has the power to transform substances of different kinds - 1?m3 of concrete is the result of clever dosages of water (150?l), sand (700?kg), chippings (1200?kg), and cement (300?kg) - into a single, highly malleable material, which can be used to model spectacular shapes, buildings, infrastructures, and the city itself in record time. This technological feat has fascinated for decades: it solidifies in 2?hours without any energy input. This metamorphosis of a natural stone into an artificial stone and a quasi-living material appears, as Taussig notes (2004: 162), almost magical:

You start with stone. You make a powder. And then in the process of building, you add water and end up with a new form of 'stone' in accord with the shape desired. It sounds like magic but we call it technology.

Concrete has become widespread across time and space to become the "world's most common man-made material" (Courland 2011). After water, it is the most widely used substance on earth (Watts 2019). In the space of one century, concrete has become an ordinary, normal, and global product. Ordinary, because nearly everyone uses it or wants to use it to meet a common human need: shelter. Normal, because its use has spread to the point that it is taken for granted, as if it was the only possible construction material for building cities, housing, and infrastructure. Global, because it is now a commodity that is sold and consumed in every country in the world. With its consumption soaring tenfold over the last 65?years (Habert et al. 2020: 559), this material is the earth's most widely manufactured product in terms of volume, ahead of plastics or steel, with 4.5?billion tons produced each year (Van Damme 2018). As a consequence, the consumption of sand and gravel has increased fivefold in the past 10?years. In his essay on concrete, David Harvey (2016) writes about concrete consumption in China, where a third of the national economy depends on construction: since 2003, it has used more concrete in every 3?years than the United States in the whole of the twentieth...