Each year, the world population consumes 50 billion tons of sand. This makes it the second most used resource, after water, according to the United Nations. In many countries, extraction is very little regulated, which in particular poses environmental problems. And at home, where does the sand that we use, mainly in construction, come from?
After water, sand is the most exploited resource on earth: 50 billion tonnes are extracted each year worldwide. “We consume more and more sand because we build more and more. It must be said that the sand is mainly what goes into the concrete. Because concrete is a pile of sand with cement to bind it all together“, explains Eric Pirard, geologist at the University of Liège.
Everything is made of concrete
Concrete, a practical, solid mix that lasts over time. In modern construction, it is everywhere. We go to a building site in Brussels. Two buildings are being completed. “Everything is made of concrete. Sails poured on site in concrete, all the floors are in concrete”, explains Hamza El Baoudi. “Here, we are on a concrete slab which is 1,500 m3“, adds the site manager, looking at the ground. 1,500m3 is more than 1,300 tons of sand.
For solid concrete, nothing beats natural sand. But beware, not that of the beaches, but of the sand pits. We take the direction of a farm in Mont-Saint-Guibert. “This sand is mainly used for masonry, it is much more compact and greasy“, says Vincent Peetroons, director of the Sablières de Mont-Saint-Guibert, presenting a handful of sand.
“This sand is used for concrete plants. For special concretes, pre-stressed and rich concretes, therefore washed“, he explains, pointing to another handle.
Fewer and fewer sand pits in Belgium
The Brabant farm is the largest in Belgium, but also the last. “In the 80s, there were more or less 80 sand pits in Belgium. Today there are maybe five left“, says Vincent Peetroons.
Impossible to extend the exploitation to infinity. By digging down, we would fall on the water tables. By digging on the sides, the sand pit would encroach on agricultural land or dwellings. “Sur has received an extension of 47 hectares, which will give us a sustainability of 25 more years of operation“, says Vincent Peetroons. “All the operators, today, have doubts about quarries, future operations, extensions… Because the territory of Belgium is too small to be able to expand further in the next hundred years“.
In an attempt to solve the problem, some real estate projects aim to recycle old buildings being demolished. But for scientists, the most effective would be to concrete less. A solution that may be difficult to apply. In the last twenty years, the demand for sand has tripled.