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Cement: Development Contributor or Constrictor?

February 1, 2016

Why dependency on the world’s second most-consumed substance oftentimes impedes sustainable development.

 

Much of the world is built solely with one single construction material, particularly countries of the Global South where construction materials industries are developing.  Yet, in the age of climate change and rapid urbanisation, cement dependency also comes with costs that can exacerbate already vulnerable conditions or counteract development aims.  We examine the causes of cement dependency, its material performance and environmental and economic effects, and lastly the various approaches to dealing with these challenges. 

 

 

 

What Exactly is Cement?

 

The terms concrete and cement are often incorrectly used interchangeably, and technically are not the same.  Cement is the byproduct of limestone, which is extracted, crushed and superheated into a fine powder.  When mixed with water, cement undergoes a chemical transformation that microscopically forms a chemical bond to the rough surfaces of various aggregates- usually sand, gravel and even sometimes organics such as palm kernel shells.  This mixture hardens to form concrete.  Simply put, cement is concrete’s binding agent.

 

 

Many countries of the Global North benefit from developed construction materials markets drawing from a diverse array of managed natural resources, worker skill sets, technological and fabrication capacity, and dependable distribution systems.  In places where these conditions are lacking or non-existent, cement is often the primary or only building material available.  While one may think cement is ubiquitous because it may be the cheapest option, in many countries cement is cost prohibitive for the vast majority of people.  

 

 

Reasons why Cement is Ubiquitous

 

Ease of Handling

Unlike large members of steel or timber requiring heavy machinery, standard 50kg bags can be handled by a single person.

 

Versatility

Cement can be used for foundations, wall blocks, patching, plaster renders, and pavements, and is usually mixed and formed on-site.

 

Low Skills and Equipment

Unskilled workers can quickly learn the material’s properties and techniques using simple hand tools.

 

Fast, Strong and Lasting

Rapid setting time reduces costs of construction, and when mixed properly, concrete can have a limitless lifespan.

 

Social Stigmas and Preferences

There is often perception that concrete is more ‘advanced’ and more modern than other materials, particularly traditional materials which ‘look poor’.

 

Absence of Alternatives

In many countries the timber supply has been completely depleted for agricultural use or by locals for cooking fuel.   Reforestation and sustainable forestry programs are non-existent, improperly managed or poorly enforced.   Insufficient supply chains and distribution networks make other pre-fabricated building components cost-prohibitive. 

 

 

The Costs of Cement

 

Material Performance

One academic study shows that concrete structures increase the interior latent heat effect compared to earthen materials, such as adobe or compressed earth blocks, which actually have a cooling effect.   Rooms built from cement simply feel hotter.  In order to maintain a comfortable indoor temperature, air conditioners must consume more energy to accommodate this greater heat load.  Multiplied millions of times in a single city, all of these compounding factors contribute to the urban heat island effect.

 

Environmental Effects

 

Energy Inputs and CO2 Outputs

In the cement production process, large batches of lime must be heated to 1400-degrees celsius, requiring constant and intense energy inputs, typically powered by imported fossil fuels.  Put into perspective, molten magma within the earth is about 1200-degrees celsius.

 

But it’s not just the energy inputs that cause ecological strain.  The chemical reactions during the calcination process itself emits CO2, making the cement industry a greater carbon emitter than the entire aviation industry.  

 

Airborne Pollutants

Other airborne heavy metals, such as mercury, are released into the atmosphere as well, eventually finding its way into food chains, including fish stocks.   Currently in the United States, the cement industry is less regulated than the coal industry.  Regulation in other countries, such as China which produces 52% of total global cement output, is lesser known.

 

Aggregates

Regarding extraction of aggregates, many developing countries have limited capacity for extracting, grinding and refining gravel and other aggregates.   Beaches and riverbanks are one common source of sand aggregates for wall blocks or mortar, creating erosion and wildlife impacts.  For example, on Cabo Verde’s island of Santo Antão, sea turtle breeding grounds have largely disappeared due to sand extraction for construction.  In Sierra Leone sand extraction is frequently only possible during dry seasons when riverbanks are more exposed and accessible.

 

 

Economic Effects

End-user costs

Currently in Kigali, Rwanda, one 50kg bag of cement averages $13.25 USD, with higher costs in rural areas where 80% of the population reside.  Considering Rwanda’s GNI per capita is $700 per year (World Bank, 2014), a single bag of cement is equivalent to the average Rwandese wages for one week.  Cement-based construction methods simply is cost-prohibitive for the majority of people in many developing countries.  This high cost is a key contributor to the current housing crisis.

 

Scale of Production Process

Due to the high energy inputs and large scale equipment costs, cement simply cannot be produced via a small-sale, cottage-industry basis.  The result is that an elite few producers are able to amass considerable influence over commodity prices. 

 

A GDP’s Achille’s Heel

When countries are dependent on a single material source for nearly all of its infrastructure and physical development, price fluctuations can shock state-level GDPs. In 2012, a lightning strike knocked out Ghana’s Diamond Cement plant, one of only two plants serving a country of 25 million.  After three weeks of halted production, cement prices skyrocketed 300%, disrupting or furloughing construction and road projects throughout the country.  The World Bank subsequently intervened and induced the Ghanaian government to diversify it’s cement industry.  This single event registered as a blip in the country’s annual GDP- a lightning strike indeed.

 

The Cement Power Play

When controlled by an elite few, this fragility creates considerable exposures to price manipulations.  Aliko Dangote, the eighth richest man in the world, and CEO of Nigeria’s Dangote Cement, has aggressively expanded cement production and processing throughout sub-saharan Africa.  Whereas in colonial eras, cement production was conducted in developed countriesUnder the motto of pan-African development by Africans, not everyone on the continent is welcoming Dangote’s heavy-handed presence.   In 2013, Dangote Cement constituted 30% of the Nigerian Stock Exchange’s worth.  In Africa’s biggest economy, 80% of Nigeria’s economic growth came from Dangote Cement alone.

 

We can see that sustainable development is often stifled not just by resource deficiencies, but by key dominators impeding diverse and robust markets from forming.   From an economic perspective, dependency on one single material for development increases the vulnerability and fragility of emerging economies.  

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