While the world is in the constant pursuit of development and growth we are faced with an endless array of old and new obstacles to overcome. The crux of these obstacles are usually related to the resources needed in order to develop. Most of us are aware of peak oil, the environmental problems associated with coal and the issues related to large scale food production. 

However, sand is something we don’t hear about too often. Sand is one of the world’s most highly-coveted commodities and is mined extensively as a construction material. Mixed with water, cement, and gravel, sand is used as a fine aggregate in the production of concrete. Concrete is made of 10% cement (lime and Clay) 15% water and 75% sand. Presently, we are using concrete at an unprecedented scale. To make matters slightly worse, sand also has other industrial uses: it is used to make glass, electronics, and to help extract oil in the fracking industry. And vast quantities of sand tend to be dumped into the sea to reclaim land

Here are some sand consumption statistics

  • To build an average single-family house: 200 tonnes
  • To build 1 kilometer of highway: 30,000 tonnes
  • Annual sand and gravel consumption worldwide: 40 billion tonnes
  • Annual sand and gravel consumption for concrete construction: 26-30 billion tonnes. 

This equates to 18 kilograms of sand per person per day.

Between 2011 and 2013, China used more concrete than the US did in the entire 20th century. Again: in Three years, China built the equivalent to every highway, road bridge in the US. Sand and gravel are now the most-extracted materials in the world, exceeding fossil fuels and biomass. Worryingly, our sand and concrete usage is likely to increase exponentially.

 

So where does this sand come from? 

Sand mining is the extraction of sand, mainly through an open pit, from beaches and inland dunes or dredged from ocean, lake and river beds. River and marine aggregates are now the main sources for building and land reclamation. However, Marine aggregate needs to be thoroughly washed to remove salt. This makes it less attractive and more expensive as a viable source. If the sodium is not removed from marine aggregate, a structure built with it might collapse after few decades due to corrosion of its metal structures. Therefore, most developing countries opt for cheaper and more accessible sources like river beds and beaches

Dredging sand from beaches is problematic due to coastal erosion and is an illegal practice in China. Therefore, China has gotten most of its sand from dredging Poyang Lake. Located in Jiangxi Province, is the largest freshwater lake in China.An estimated 236 cubic meters of sand are taken from it every year, making it the largest single sand mine in the world. All this sand mining has had a devastating effect on the lake and the ecosystems it supports. High-density dredging projects have been the principal cause of the death of the local wildlife population. In 2016, the lake nearly dried up completely. Only 200 square kilometers of land was underwater in October, while the lake is normally 3,500 square kilometers in area when full.

Who would’ve thought that such a simple and seemingly omnipresent resource can be such a problem. And yes, I know what you’re thinking, and no, we can’t use sand from the desert. The sand that is found in most deserts is paradoxically unsuitable for concrete and land reclaiming. Wind erosion makes the grains too round for most purposes. We need angular sand that interlocks like pieces to a puzzle. For example, dune sand taken from desert sources does not bind well in concrete mix and may only compose a small percentage of aggregate.

Therefore in Africa, the Sahara, which contains an almost endless amount of sand, is basically completely useless. Instead, sand miners must look to the banks of local rivers and coastlines, and this brings a whole host of environmental and human problems. In Africa, a lot of the sand being used for construction comes from the coasts of Ghana and Kenya, as well as those of Cape Verde and Zanzibar.  Official statistics from the Department of Forestry and Non-Renewable Natural Resources show that almost 3 million tons of sand were mined on Zanzibar between 2005 and 2015. This amount equals around 120,000 full truckloads.This is only the official mining. The number for illegal mining is probably double that amount. In Morocco, half of the sand – 10 million cubic meters a year – comes from illegal coastal sand extraction. Sand smugglers have transformed a large beach into a rocky landscape between Safi and Essouira.

 

Why is this a problem? 

Well the problem twofold. First, is the environmental impact related to concrete and cement generation, and the second, is the actual impact of sand mining. So let’s start with cement and concrete production. 

Cement production is the third ranking producer of anthropogenic (man-made) CO2 in the world after transport and energy generation. CO2 is produced at two points during cement production: the first is as a byproduct of burning of fossil fuels, primarily coal, to generate the heat necessary to drive the cement-making process. The second from the thermal decomposition of calcium carbonate in the process of producing. Cement has to be heated to very high temperatures in order for clinker to form. A major culprit of this is alite (Ca3SiO5), a mineral in concrete that cures within hours of pouring and is therefore responsible for much of its initial strength.

Furthermore, as you might have realized, sand mining also has an enormous impact on the physical environment and also leaves lasting scars that will be problematic over the course of time. So just how problematic you ask? 

Well, If you’re planning a beach vacation, you’d better get to it soon. An alarming statistic for you: 67% of Southern California beaches? Gone by 2100. Some experts estimate that up to 90% of the world’s beaches have shrunk an average of 40 meters since 2008. Worldwide, illegal sand mining has destroyed entire islands. Two dozen Indonesian islands have disappeared around the same time Singapore imported 17 million tons for it’s massive 50-mile land expansion.

In Sri Lanka, research has revealed that intensive sand mining prior to the 2004 tsunami made the waves more devastating than they otherwise would have been. In other words, the beaches disappeared, and so there was no natural barrier stopping the flooding. beaches act as an important buffer between the ocean and people providing protection for storm water surges and tsunamis. 

The recent floods in Houston were actually made worse by sand mining in the San Jacinto River. The San Jacinto is one of the rivers that borders Houston. It’s also an excellent source of sand. It has been mined very heavily for sand for the past 20 years.

Another example is of the Mekong delta, the world’s third largest delta and which hosts a population of nearly 20 million and is also crucial to the food security of Southeast Asia. The delta is currently sinking due to a lack of sand. River deltas crucially depend on sustained sediment supplies in order to maintain delta shoreline position and to balance subsidence. Because they are increasingly starved of sediment trapped behind the dam reservoirs and now the excavation and dredging of sand, many of the world’s river deltas are becoming vulnerable to accelerated subsidence and erosion, losing large tracts of land and becoming more exposed to flooding and sea-level rise. 

The fact of the matter is this: it is now widely accepted knowledge that we will face severe consequences due to climate change. NOAA scientists predict  that global mean sea level will rise at least 8 inches (0.2 meter) but no more than 6.6 feet (2.0 meters) by 2100. This is a worrying statistic because, globally, 8 of the world’s 10 largest cities are near the coast. At a time when we should be focused on climate change mitigation and adaptation, we are seemingly aggravating the problem by weakening our protection against sea level rise and storm surges. By removing sand from our rivers and oceans we are drastically increasing our exposure to risk. Sand mining also has other detrimental effects on environmental sustainability, illustrated in the table below. 

Impacts on Description
Biodiversity Impacts on related ecosystems (for example fisheries)
Land losses Both inland and coastal through erosion
Hydrological function Change in water flows, flood regulation and marine currents
Water supply Through lowering of the water table and pollution
Infrastructures Damage to bridges, river embankments and coastal infrastructures
Climate Directly through transport emissions, indirectly through cement production
Landscape Coastal erosion, changes in deltaic structures, quarries, pollution of rivers
Extreme events Decline of protection against extreme events (flood, drought, storm surge

 

Extraction has an impact on biodiversity, water turbidity, water table levels and landscape and on climate. There are also socio-economic, cultural and even political consequences. The problem is now so serious that the existence of river ecosystems is threatened in a number of locations, damage being more severe in small river catchments. The same applies to threats to benthic ecosystems from marine extraction .

 

Are there any solutions? 

Governments worldwide have begun to regulate and restrict sand mining and concrete production. Now Problem solved, right? Actually, It’s caused an entirely new problem: Profits from sand mining frequently spur profiteering. Today organized crime groups in India, Italy and elsewhere conduct illegal trade in soil and sandThe Black Market of Sand Illegal sand mining has lead to the rise of the Sand Mafia, India’s strongest criminal organization. Another example is of Singapore, the world’s largest importer of sand, which has added 130 km of coastline These high-volume sand imports have drawn it into disputes with Indonesia, Malaysia and Cambodia

So is it all doom and gloom? No, luckily there are viable options and measures that can be taken to circumvent this looming crisis. Fortunately, there are substitutes for sand: asphalt and concrete can be recycled, houses can be built with straw and wood, and mud can be used for reclamation. Both natural and artificial alternatives to river and lake sand are available. Germany, for instance, recycles 87% of its waste aggregate materials. Recycled ash from burned solid waste can also replace sand, but this is a costly exercise which most developing countries can’t and won’t afford.

There are also a number of practical, scientific and governance related measures which can be implemented by organizations and individuals to try and reduce the immediate and long-term impact of sand mining and concrete production. But more on that later on… 

 

So what  does this all mean for Africa? 

Africa is home to a rich and diverse animal, plant, and marine biodiversity that provide critical ecosystem services, driving the continent’s economy and serving as buffers to climate change. With the new African trade deal soon to take effect, Africa is on the cusp of extensive development and growth. This growth will require infrastructure and housing and that requires concrete. 

15 planned mega infrastructure projects that will transform Africa

From what we have learnt so far, this is a problem. Africa is currently losing biodiversity at an unprecedented pace. It is estimated that by 2100, climate change alone could cause the loss of over half of African bird and mammal species, as well as trigger a 20%–30% decline in lake productivity (the plant and animal life produced by a lake). Sand mining, especially if pursued like it currently is and how it has been done in China, will only hasten and drastically worsen these environmental impacts. 

With a huge infrastructure gap to fill—about US$93 billion per year—and renewed efforts by national governments and development partners to invest in infrastructure development, the demand for construction is expected to increase further in the coming years. Cement consumption Sub-Saharan Africa grew by 6.6 percent in 2014, the highest in the world 

A value chain analysis shows that the rising prices of building materials, large shares of imports, and inefficiencies in the construction process are the main factors that lead to the high costs of housing construction in Africa. This will inevitably translate to individuals and companies taking a “do whatever it takes” approach to getting sand. This will be bad for the environment and it will create and sustain a black market. 

 

So what can Africa do? 

Evidence has shown that legislation regarding sand mining and extraction around the world is either insufficient or not enforced adequately due to corruption, the absence of monitoring, or resources to prosecute offenders. Part of the challenge is that the sand industry is fragmented and significantly informal in some parts of the world. It can be a complex value chain as artisanal and small-scale operations are legion in the sector. But there are reasonable, and in some cases, cost effective measures that can be taken to minimize the lasting impact of sand extraction and the use of concrete. 

Awareness

  • A lot more can be done to raise awareness about the current and future state of the issue in relation to environmental and social impacts in the public and private sector 

Knowledge and science

  • How much sand is required for the future under different demand scenarios, acknowledging different forms of development and the rate of population growth? 
  • What is the real cost of unsustainable sand resource extraction and consumption, including externalities associated with its extraction and use?
  • Sand is not equally distributed around the world or within states. Where is it in relation to projected demand? And how can this supply chain be made more efficient and sustainable? 
  • Who is involved? What can they do? How will they be affected? Who owns the rights to sand resources and the land, rivers or marine areas from which they are extracted?

Transparency and accountability 

  • Accountability is something that needs to cross boundaries and borders, right down the value chain. While we may know how much sand is being extracted from a location, we rarely know where it goes

Best Practices 

  • We can do better to avoid unnecessary consumption by improving planning by pursuing urban design that promotes density and by avoiding surplus construction projects 
  • Employing green infrastructure in place of built infrastructure where possible.
  • Substituting traditional concrete where possible 
  • Reusing waste aggregates on construction sites, recycling concrete from waste asphalt and substituting fine aggregates (sand) and coarse aggregates (gravel) in concrete production 
  • Innovating on concrete designs to increase materials efficiency and environmental performance, with: • Foamed concrete • Geopolymer concrete

To conclude, clearly we are facing a crisis that has not yet permeated the mainstream media. However, Africa sits in an extraordinary situation where it can proactively address these issues before they become a problem for Africans. Experts have identified the problem, know its causes and know how to solve it. It is up to us, governments and the private sector to make sure that we address this problem with the respect it deserves. Before the proverbial sands of time run out. 

 

One thought on “Sands of Time – The Devastating Impact of Concrete

  • Stephen Saunders

    Dear Kyle, I appreciate your rather long article and the fact that you used a very neat table, a pictograph image (map), bulleted sections, and both standard and bold headers. Who would ever guess that sand can be such a problem? It takes someone like you to illuminate us, inform us, and set the record straight.

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