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FEATURE: Sands of time – clock ticking for construction during aggregates shortage

John Osborne

River sand, a vital material for construction, is in short supply in some areas of the world (Credit for all images: Shutterstock)
River sand, a vital material for construction, is in short supply in some areas of the world (Credit for all images: Shutterstock)

The world is running out of sand.

That might not seem like a big problem, but river sand – which is facing the biggest shortfall – has unique properties that make it useful for all kinds of construction, and particularly in the manufacture of concrete.

River sand retains its sharper edges and is significantly more suitable for use in concrete than the sand that most people are familiar with – the type found on beaches and in deserts. In its absence, engineers and architects are being forced to find new, more sustainable alternatives.

“In the global debate about the availability and consumption of ‘sand’, what is usually being referred to are construction aggregates,” says Guy Thompson, who is head of architecture, housing and sustainability at the Mineral Products Association. “Aggregates are a major constituent of the mineral products industry, and essential to our economy and way of life. At the same time minerals are a finite resource and the supply should not be taken for granted by society, industry or the government. Our needs have to be supported by sustainable, well-managed supply chains.”

Both the United Nations and the Organisation for Economic Co-operation and Development have made forecasts estimating that the global demand for primary materials will double by 2050. While we are not running out of sand on a national level, globally the problem is being driven by higher demand for resources. This is owing to population growth, greater affluence and more urbanisation. There is potential for global shortages and unregulated extraction will have consequences. 

Shortages arise

Minerals can only be worked where they are found, which can create a geographic imbalance where some areas are net producers and others net consumers. “The shortage affects some countries more than others, particularly Africa, China and India,” says Andrew Waugh, founder of Waugh Thistleton Architects.

“The world is not running out of sand or aggregates, but there may be local shortages,” says Robina Longworth of the Mineral Products Association. “Globally aggregates are also sourced from fossil deposits (sand quarries), offshore marine-dredged sand and gravel, and crushed rock.” In some parts of the world there is unregulated removal of river/ beach sand from sensitive ecosystems (similar to illegal logging). While globally countermeasures are not being implemented to a satisfactory degree, the UN highlights the European Union, and the UK particularly, as exceptions in this regard. In the UK economy, minerals represent the largest materials flow. The regulation and implementation of sand and aggregates extraction in the UK is robust. 

High standards

Extraction in the UK focuses on relict or fossil geological deposits, rather than resources associated with active geological systems such as sand from rivers. We have high operational standards, and restoration of sites to increase biodiversity is required. However, globally, the introduction of scientific mining operations, followed by ecological restoration, is needed, with greater consideration of substitutes and sustainable use of the resource to reduce impact on the environment. “Ensuring the extraction process remains sustainable in the future is central to the way our industry operates,” says Thompson. 

Longworth explains: “The issue is not that we are running out of aggregates geologically, it is that extraction needs to be better regulated so that sand and aggregates are sourced from appropriate sites. 

“Synthetic sand is manufactured from crushed rock. It is used a lot in Japan, where they had issues with unsustainable extraction of sand from rivers. Process technology that crushed rock to produce a more natural sand was used. Now a large proportion of their sand demand comes from manufactured sources – where they crush down rock to create sand fractions. But it comes at an energy/carbon cost.”

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However, it is not simply a matter of using synthetic aggregates rather than increasingly precious natural ones. Engineers are likely to be caught up in political debates about their use of natural resources in construction. Added to that, all alternative and new materials must be rigorously tested and even when standards are available there will be cost and supply-chain issues as well as concern about using unfamiliar alternatives which could be fake.    

“While synthetic aggregates may seem like the solution, some lightweight materials, like plastics, have much larger environmental footprints than heavy materials like aggregates,” says Thompson. “Equally, consideration needs to be given to the fact that the production of manufactured sands requires specialist equipment alongside considerable energy, and may also require more water and cement compared to natural aggregates when being used to produce concrete.”

Waugh says his firm works hard to use more environmentally friendly and more sustainable construction materials. “Approximately 50% of all greenhouse gases come from the processes used to make construction materials and in London about half of landfill comes from construction sites. So Waugh Thistleton Architects tries to use alternatives to cement and concrete.”

Alternatives needed

Waugh says he is concerned because a lot of the traditional construction materials are single use, rather than materials that could be recycled and used again. “In the future we will need to re-engage with the way we use those materials. We will always have a need for concrete but we have to ensure that we are not starting a journey down a new path of problems. We have to find alternative forms of construction.”

Engineers are also likely to have to deal with increasingly more complicated materials and technology options as composites become more popular. Added to that, all this knowledge has to be passed onto the next generation. It will be interesting to see how young engineers respond to a global problem with enormous local implications.


Managing increased demand for aggregates

Guy Thompson, head of architecture, housing and sustainability at the Mineral Products Association

There are four key issues we need to address to better manage the impacts of the increased demand for aggregates.

First, future urbanisation needs to be well planned and resource efficient. A way to achieve this is to reverse the trend of cities sprawling. More condensed cities will require less physical infrastructure, reducing the demand for primary materials.

Second, the proper regulation and enforcement of supply materials needs to be ensured. As the UN reports, sand loss hasn’t yet reached the agendas of political leaders because the scarcity is not yet at a level that would threaten the economy.

It is unrealistic to expect the same level of regulatory practice from developing countries, but, as the price of sand increases, so will illegal trade. This already occurs in other natural resource industries, such as the timber supply chain.

The UK should put more effort into sharing with developing countries our regulatory and operational expertise. Mineral operations in the UK can provide excellent examples of global good practice, both to mitigate and manage potential impacts and to deliver biodiversity and environmental net gain through effective site restoration.

Third, resource and minerals businesses have a responsibility to act sustainably and to evidence such responsibility, for example through independently audited environmental management and responsible sourcing standards. 

Finally, we need greater transparency about the governance and activities of minerals and other natural resource industries and the associated revenue flows. The international Extractive Industries Transparency Initiative is designed to increase such transparency and create a platform for debate about the governance of the sector, but further progress is required.


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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.
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