Is our love affair with concrete over?
Written by
Joe Clough - Graduate Sustainability Consultant
To contact please email: joe.clough@mainer.co.uk
COP27 is currently underway in Sharm El-Sheikh, Egypt where a group of 198 countries that have signed the UN Framework Convention on Climate Change. If it were a country, concretes CO2 emissions would make it the World’s 3rd largest. Joe examines why concrete is so popular, the price we pay for it and what is the sustainable future of concrete?
Why do we love concrete so much?
Concrete offers a diverse and flexible building material when it comes to construction and can be moulded and shaped for a variety of different purposes.
Cement is the most utilised material on earth and as the main element in concrete, when mixed with water, fine and coarse aggregate it becomes a strong, durable and popular material. Concrete was used in construction as early as 6500BC and now due to its abundant availability, every home, building and road you look at today is predominantly made up of concrete.
What price do we pay for concrete popularity?
Cement production as the largest element of concrete, is responsible for an estimated 7% of global carbon emissions. To put that in perspective if the cement industry was a country, it would be the third largest emitter of CO2 in the world.
Carbon Dioxide (CO2) is produced at two stages of cement production.
Stage 1 - The burning of fossil fuels in production
Stage 2 - Through the thermal decomposition of Calcium Carbonate when producing the cement clinker.
Currently the world produces around 4.4 billion tonnes of concrete annually due to the rise in population density and economic development. This then drastically contributes to global warming and its associated impacts on the environment. In more recent years however, the cement industry has committed to reducing production emissions significantly in line with global targets and has already come a long way in doing so.
City of Nelsons Materical Carbon Emissions Guide March 2022 Source: Builders for Climate Action
What is the concrete industry trying to do?
The concrete industry has made progress in reducing its carbon emissions with the industries adoption of the BRE’s responsible sourcing certification scheme, BES 6001, in 2008. Currently, more than 91% of all concrete is certified to BES 6001, with around 90% having achieved 'Very Good' or 'Excellent' performance ratings. The UK is now also committed to becoming net-zero by 2050, of which the construction industry will have an important role to play in meeting this target.
The key factors for a sustainable future for the cement industry include:
Energy efficient production technologies
Example of a modern Clinker Cooler
Source: ZKG Cement
The production process of cement production is typically the most energy intensive stage with average production plants consuming around 4 GJ of energy to produce one ton of cement. Implementing new energy efficient production technologies to replace outdated equipment, is a good strategy in reducing energy consumption in the industry.
At each operation forming the production process, there are a wide range of new technologies to reduce energy wastage. Thermal optimisation techniques such as the installation of modern clinker coolers can reduce thermal energy consumption throughout the production process.
Alternative raw materials in the concrete mix
Burnt Oil Shale
Photo Source: Naturphilosophie
Using naturally occurring or industrial by-product materials as clinker substitutes in the production of cement, can not only reduce cements carbon footprint, but also supports the circular economy. Burnt oil shale is an example of a by-product from shale oil power plants that can be used as a replacement for clinker in cement.
Supplementary cementitious materials (SCM) such as Burnt oil shale can also reduce the cost of production through replacing the expensive clinker content meaning materials such as these can have dual benefits for the environment and the economy.
How does Carbon Capture work?
Photo Source: The Nature Conservancy
Carbon Capture and utilisation
To fully close the CO2 loop in the industry, carbon capture will need to be deployed industry wide at stages during and after the production process. Indirect calcination is one process whereby the CO2 released by the calcination of the limestone is separated from the emissions from fuel combustion.
This separation means that the CO2 is easily captured, and no further treatment is required. Process CO2 emissions account for two-thirds of those produced during cement manufacture, so technologies such as indirect calcination will be vital in producing sustainable concrete into the future.
Reduce/replace concrete in building projects
A built environment beyond concrete is looking very promising and could bring with it more benefits than problems.
Humanities desire for sand could rise 45% by 2060 and as a major component of concrete this poses serious problems for concrete production. This could mean switching to the use of environmentally friendly building materials such as timber and recycled steel.
Hanover Olympic Building, Hollywood
Photo Source: TCA-Architects
The Hanover Olympic building was the first net zero residential place built in LA which used sustainable materials like recycled glass and reclaimed wood along with a lightweight design to produce a net zero construction.
Clients can also achieve credits for responsible sourcing within the BREEAM, Home Quality Mark (HQM), CEEQUAL and LEED sustainability assessment schemes.
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