China and India rely largely on national supplies of sand – to minimise transport costs – but as the skyscrapers rise in Shanghai and Mumbai so does the price of this once-humble ingredient. Mumbai, India’s commercial capital, is one of the world’s top 10 mega-cities, with a population of 22m. The population of India, second only to China in its hunger for concrete, is expected to grow from 1.32bn to 1.7bn by the middle of the century. By 2050, two-thirds of humanity will live in urban areas, a product of migration and population growth. Aggregate is the main ingredient for roads, and China laid down 146,000km of new highway in a single year. Between 20 it used more concrete than the United States did in the entire 20th century. View image in fullscreen The Burj Khalifa, Dubai: ‘Despite being surrounded by sand, it was constructed with concrete incorporating the “right kind of sand” from Australia.’ Photograph: Bloomberg via Getty ImagesĬhina leads the charge in today’s sand-fuelled construction boom, consuming half the world’s supply of concrete. Marine sand from the seabed is also used in increasing quantities, but it must be cleansed of salt to avoid metal corrosion in buildings. Riverbed sand is prized, being of the correct gritty texture and purity, washed clean by running fresh water. Despite being surrounded by sand, it was constructed with concrete incorporating the “right kind of sand” from Australia. A textbook example is the Burj Khalifa in Dubai, the world’s tallest skyscraper. Sand, sand everywhere, nor any grain to use, to paraphrase Coleridge. Builders like angular sand of the kind found on riverbeds. Wind action in deserts results in rounded grains that are too smooth and too small to bind well in concrete. Our need for concrete is such that we make almost 2 cubic metres worth each year for every man, woman and child on the planet.īut what of those oceans of sand stretching from the Atlantic to the Persian Gulf – the Sahara and the Arabian Desert? The wrong kind of sand, unfortunately. Of the 15 to 20bn tonnes used annually, about half goes into concrete. Global production has risen by a quarter in just five years, fuelled by the insatiable demands of China and India for housing and infrastructure. Sand is second only to water as a natural material extracted by humans, and our society is built on it, quite literally. Enough material to build a wall 27m high and 27m wide around the equator. The world consumes between 30 and 40bn tonnes of building aggregate a year, and half of this is sand. Our insatiable appetite for new buildings, roads, coastal defences, glass, fracking, even electronics, threatens the places we are designed by evolution to love most. Yet sand in the right places is anything but infinite.
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