Built on sand: Is the construction boom depleting supplies?

Sky-scrapers, airports, motorways and artificial islands –such huge projects realised as part of the unprecedented construction boom in many countries over the past 15 years have increasingly exhausted sand resources. This means that concrete, a building material for which in many cases there is still no alternative, may soon be in short supply. "As common as sand" – this German idiom has always stood for a resource that is commonly available and thus of no great (apparent) value. But as far as sand is concerned this may soon be a thing of the past, according to a recently published report by the United Nations Environment Programme (UNEP). In recent years sand has become a rare commodity in many regions of the world, and with good reason. If a wall were built around the equator out of the concrete produced every year all over the world, it would have to be 27 metres high and 27 metres wide. The building branch – including concrete construction and road construction first and foremost – has by far the greatest worldwide demand for the aggregate, largely for producing the cement that goes into concrete. Other industrial applications, such as production of solar panels or cosmetics, which both require silica crystals, account for less than five percent of all sand consumption.

Even resources experts seem surprised by the new dearth of sand, as the title of the UNEP report – "Sand, rarer than one thinks" –– would indicate. This may be because only certain regions of the world have been experiencing an acute scarcity of the aggregate so far. For Germany, this is not an issue – differing it from countries like Dubai that would seem highly unlikely candidates for the problem. Yet the emirate's sand (like that in many other desert countries) cannot be deployed in concrete, as its wind-eroded round grains do not bind well in producing cement. This differs it from all sand and gravel deposits in riverbeds and the sea. These are suitable for construction use, particularly once marine sand has been thoroughly rinsed to rid it of the salt that would soon corrode concrete rebars.

Dubai has now basically exhausted its own marine sand resources in building the Palm Jumeirah and Palm Jebel Ali sets of artificial islands, and more recently The World archipelago, and had already had to transport huge amounts of sand from Australia thousands of kilometres away to construct the Burj Khalifa tower, at 828 metres is the highest building in the world. In 2012 the nearby emirate of Qatar was the world's largest importer of sand and gravel, namely to the tune of 6.5 billion dollars. In the same year the huge country of China managed only half the amount.

But it is mainly the smaller (city) states that obtain sand from other countries. For example Singapore has increased its land area by more than 20 percent over the past 40 years using sand removed in enormous amounts from beaches in Indonesia and Malaysia.  Now that the governments of the respective countries have banned such sand mining, the aggregate is excavated illegally in many places. As Germany's respected weekly Die Zeit and the Swiss Tagesanzeiger report, sand mafias have come about not only in Southeast Asia but also in India and North Africa.
 
For Germany, this problem seems relatively far away, for the moment at least. So far the country's economy has not had to reply on imports of sand and gravel (in contrast to oil, natural gas and ores). But the speed with which sand has been depleted in many regions of the world should be a warning to the German construction branch, namely that no resource is infinite. Thus it is all the more important to take the three R's of sustainability to heart: Reduce, reuse, recycle. Far too many buildings are still demolished, particularly in prestigious locations, to be replaced with new ones instead of seriously considering how the existing ones could be put to new use. Nor are things much better on the road construction front. There is so little funding available for this purpose that the existing infrastructure can barely be kept in decent shape, yet road projects go on being registered for the 2015 Federal Transport Infrastructure Plan like a wish list for bypasses and other new roads.  

More research needs to be conducted into alternatives to use of fresh sand and gravel in concrete construction. Switzerland, for example, has been subsidising use of aggregate incorporating recycled concrete for years, whereas in Germany the concrete from demolished buildings tends to end up in the base course of roads – a classical example of downcycling, i.e. putting waste materials to poor use.  

Concrete can frequently be replaced with other building materials if statutory conditions permit. For example, wood construction experts have long called for easing of the fire protection regulations that often make timber construction an unnecessarily expensive business. But even here caution is advised: our forests do not have endless supplies of wood. Due to the increasing amounts of timber burnt in pellet stoves and heating power stations, the annual net increase (newly-grown amounts of wood minus the amount harvested) in German woods has rapidly been reaching zero point in recent years.

In other words, the only things that will really help over the long run are efficiency and thriftiness in use of all resources, including renewable ones, not to mention avoidance of the speculative bubbles that come about through massive construction of housing and office space surplus to all requirements. Future generations will probably have to pay a high ecological and economic price for such politically-fostered and thus artificial boosts to the building trade. Cautionary tales of squandered resources abound, particularly concerning such growth regions of the world as Dubai, where over 30 percent of all office space was empty in 2013. Or take the case of the desert city of New Ordos in western China, designed for 300,000 and home in 2012 to a mere 5,000. 

Sand use in figures

Sand consumption for an average single-family house: approx. 200 tonnes
Sand consumption for one kilometre of motorway: approx. 30,000 tonnes

Annual sand and gravel consumption worldwide: approx. 40 billion tonnes
- thereof for concrete construction: 26-30 billion tonnes
- thereof for industrial purposes (such as production of electrical devices, cosmetics and solar panels): 180 million tonnes

Sand volume of the Palm Jumeirah artificial island in Dubai: 385 million tonnes
Annual extraction of sand and gravel in Germany: 235 million tonnes
Amount consumed by the construction industry. 95 %

Singapore's sand import volume since 1995: 517 million tonnes
Increase of land area in Singapore since 1975: 130 square kilometres
Average price of sand imported by Singapore between 1995 and 2001: US$3 per tonne
Average price of sand imported by Singapore between 2003 and 2005: US$190 per tonne

Annual per capita consumption of sand in Singapore: 5.4 tonnes
Annual per capita consumption of sand in Europe: 4.6 tonnes