By Maddi Langweil, Stanford University
The ongoing surge in demand for sand has made it a scarce commodity. This natural resource is commonly used in computer microchips, construction, and is an active ingredient in cosmetics. But the current supply of this material has not been able to keep up with the speed of global urbanization. Now, sand is approaching a cost of $10 a ton, while it was just under $4 a ton 31 years ago.
While sand can be found in almost all countries, there is a specific type of sand most desired by society — sand with an irregular shape. This kind of sand enables products to be stronger than smooth and symmetrical grains of sand, but such sand is only found in certain environments, like the bottom of rivers and streams.
To address the shortage, alternatives such as glass or M-sand — manufactured sand — have been deemed to be a suitable substitute for those unable to access natural sand. Even with all the interest in various alternatives, Stanford geographer and environmental scientist Eric Lambin emphasizes that, “a complete physical sand depletion globally is unlikely.”
Impacts of a Sand Shortage on Buildings
The sand found in deserts is unsuitable as construction material because it has been eroded by wind, making its sand grains smooth and they do not bond well together. That is why the tall buildings of Dubai, a desert city, were built with sand imported all the way from Australia — as skyscrapers require extremely high-quality aggregates. High-income countries will continue using high-quality materials by importing them from distant places, thus offshoring mining impacts and increasing transportation costs.
In countries with high demand for sand and poor regulations, once high-quality deposits become exhausted or inaccessible due to urban growth, nature protection, or farming, sand extraction shifts to low-quality materials with organic matter or salt that, when used for the wrong applications, increase the probability of construction failure and building collapse. Construction failures have been linked to poor sand quality in Haiti following the earthquake, Nigeria, Morocco, Thailand, South Africa, and Italy.
Big picture, it’s important to remember that it’s unlikely we’ll deplete sand on a global scale. What we do observe are regional sand scarcities — with both physical scarcities ensuing when demand exceeds physical availability, and economic scarcity resulting from loss of access to sand deposits due to competing land uses or local opposition to mining due to environmental impacts.
Cost Effects of Sustainable Materials
The problem is that sand extraction is largely unregulated. It is, therefore, a rather cheap resource, even though its extraction causes damaging impacts on land, freshwater, and coastal ecosystems. For more sustainable construction materials to be competitive, regulations on sand extraction need to be more stringent and better enforced. In several countries, organized criminal groups, known as sand mafias, have taken control of the sand trade and they don’t hesitate to use violence against anyone opposing their destructive extraction practices. These illegal activities distort sand markets and stifle innovation.
Some have proposed using recycled glass as a replacement for sand, but is this a viable alternative?
The technology to crush glass into a material equivalent to sand does exist and is already in use, for example as an alternative to sand for pool filters. However, it is more economical and environmentally friendly to wash glass bottles and reuse them as many times as it is possible rather than transforming them into sand. Even if all recycled glass were transformed into sand, it would produce nowhere near the 40–50 billion metric tons of sand, gravel, and crushed rock used every year around the world.
Instead of mining unconsolidated sediment deposits, fine-grained sand and coarser products can be produced artificially by crushing rocks or by recycling construction and demolition waste such as concrete or masonry. Crushed rock can be equally suitable or superior for some applications, thanks to better control over mineralogical composition and shape. It is already the main source of aggregates in the United States, Europe, and China.
Engineered timber is another promising alternative construction material, which also contributes to carbon storage, but it is only suitable for low- and mid-rise buildings.
These alternatives will only be deployed at a scale once sand extraction is better regulated, and the price must include the environmental externalities associated with its extraction and transport. RB
As told to Maddi Langweil, Stanford University by Eric Lambin, Geographer and Environmental Scientist, Stanford University