The second natural resource most exploited to the world after water is starting to run away: sand. Not that of the deserts, unsuitable for building, but that taken from rivers and coasts at a rhythm that is devastating the ecosystems. While the problem becomes global, China seems to have found a large -scale solution, almost completely replacing natural sand with an artificial, produced by rocks and industrial waste.
The problem hidden in a grain of sand
Sand is essential to produce the concrete necessary to build houses, roads and infrastructures. Every year, humanity extracts about 50 billion tons, an unsustainable figure. The intensive extraction, however, has a very high cost: the removal of sand from rivers and coast accelerates its erosion, increases the risk of floods, degrades aquatic ecosystems and threatens the coastal communities. In addition, it can contaminate or lower the aquifers, putting at risk the availability of drinking water for people, animals and agriculture.
Why not use desert sand? The answer is in its form. The grains of desert sand, smooth by the wind, are too smooth and rounded to tie effectively with the cement. On the contrary, the sand of river or marine origin has a more angular and rough grain, essential to guarantee the stability and resistance of concrete.
“The issue of sand surprises many, but it should not. We cannot extract 50 billion tons per year of any material without causing enormous impacts on the planet and therefore on people’s lives,” he told BBC Pascal Peduzzi, researcher of the United Nations program for the environment (Unep), underlining the severity of an often ignored crisis.
The Chinese turning point: from necessity to virtue
China, protagonist of unprecedented urban growth in the last 40 years, has clashed hard with this problem. The exponential demand for building materials led to a massive exhaustion of natural sand reserves, with consequent degradation of over 40% of the cultivable land. Around 2010, with the natural reserves and sand prices, the government has intensified the fight against illegal action, pushing the construction industry to urgently seek alternatives.
The solution was found in artificial sand: a material produced by the mechanical crushing of rocks or, in an even more virtuous way, by the waste and residues of the mining activity. This process is not only cheaper, but it is also decidedly more ecological, since it does not disturb the delicate balances of rivers and beaches.
A “miraculous” transition certified by the data
A study published in Nature Geoscience analyzed the consumption of sand in China between 1995 and 2020, revealing a surprising transition. Although the production of artificial sand began in the early 2000s, it is only after 2010 which saw a mass adoption.
In 2010 the supply of natural sand reached its peak, but already from the following year the artificial one overcome it, becoming the main source for constructions. Since then, its production has grown at a rhythm of 13% per year. The result is that in 2020 the natural sand represented just 21% of the total offer of the country, with a collapse of almost 80% compared to ten years earlier. “The overall offer of China sand has increased by about 400% in the study period, but the percentage of natural sand fell from about 80% to about 21% due to the growing use of artificial sand”, observe the authors of the study.
This transition has been called a “miracle” by Song Shaomin, professor of the University of Civil Engineering and Beijing architecture: “The percentage of artificial sand on the Chinese market could now reach almost 90%”.
The Chinese model shows that a sustainable alternative is not only possible, but also practicable on a large scale. However, further research is needed to evaluate their applicability in other geographical contexts and to understand the environmental impacts related to its production, which still depends on quarry and mining activities.
