Concrete and carbon dioxide
Concrete has many excellent properties that are prerequisites for sustainable construction. But concrete also has an environmental impact. This is mainly due to emissions of carbon dioxide from the production of cement, which is one of the binders in concrete. Cement is an adhesive that can mixed with water to bind together stone, gravel, and sand form concrete.
Globally, the cement industry accounts for about 7 % of carbon dioxide emissions. That is significant, of course, but it is important to remember that concrete is the world’s most widely used building material. Today, more than 30 billion tons of concrete are used per year.
Concrete is used to build roads, bridges, tunnels and railways, ensure water and energy supply security and safe sewage management, and to build homes, schools, hospitals and offices.
Concrete absorbs carbon dioxide
Many people are probably unaware that concrete absorbs carbon dioxide throughout the lifetime of a concrete structure, which is known as carbonation. This occurs quite naturally and usually does not affect the structure’s properties.
Up to 20 % of carbon dioxide emissions from concrete production can be absorbed. There are standardized methods for calculating the carbonation of concrete (EN 16757). In Sweden, around 300 000 tons of CO2 are absorbed per year through carbonation.
Cement for climate-neutral concrete
Concrete’s major climate challenge is cement. As much as 90 % or more of the emissions from concrete come from the cement, which is one of the binders in concrete. The rest comes from transport, manufacture of concrete, and other constituent materials.
It is important to point out that the Swedish cement industry has a vision of producing cement for climate-neutral concrete by 2030. Carbon capture and storage (CCS) is a prerequisite for making that vision a reality. Norcem in Brevik, Norway, has demonstrated in recent years that there are technologies that enable carbon capture. By 2024, the global cement industry could have its first CCS plant. The aim is to have a similar solution in place in Sweden by 2030 at the latest..
The concrete industry in Sweden is aiming to bring climate-neutral concrete to the market by 2030, and for all concrete in Sweden to be climate neutral by 2045. This work is progressing under the Swedish Concrete Initiative project.
The road to climate-neutral concrete construction
Replace cement with alternative binders
The use of cement in concrete is already being reduced by both optimizing the composition of concrete and by replacing the cement with alternative binders. These alternative binders are residual products from other industries, such as slag from the steel industry and fly ash from the energy sector.
There is now concrete on the market with up to 50 % lower CO2 footprint..
! This needs to be in greater demand and used to a greater extent than is currently the case.
Optimize design at an early stage
Through resource-efficient design, material optimization, and solutions that utilize concrete more efficiently based on function, it is possible to reduce the climate impact of a structure.
Efforts such as these provide an immediate reduction, as a smaller quantity of concrete needs to be manufactured and transported. The potential varies depending on the conditions of the project, but is estimated to be over 30 %. By choosing a resource-efficient design solution right from the start, a significant improvement can be achieved.
Utilize the energy efficiency of concrete
Concrete has a high thermal inertia, which means that the temperature in a concrete building is stable, even when the outside temperature varies.
The high density of concrete also means that heat loss is minimized. That results in turn in low energy consumption, without the extra need for heating or cooling. This saves energy and money, and offers lower carbon dioxide emissions throughout the lifetime of the building.
Use the right concrete in the right place
As a starting point for optimization with regard to climate impact, it is important to avoid using a higher concrete specification than the structure requires.
“The right concrete in the right place” means that the choice of concrete quality is optimized, taking into account its climate impact.
This contributes to a lower climate impact from the building – for the same benefit.
Interact and exploit the potential
Collaboration between the developer, designer, architect and building materials supplier in the early stages of a construction project creates huge potential for reducing carbon dioxide emissions.
Concrete is always produced close to the construction site (within 1 hour), using locally sourced materials, which results in short transport distances and low carbon dioxide emissions.
Properly designed concrete buildings last for a very long time, and require minimal maintenance. This leads to cost savings and reduced carbon dioxide emissions.
Recycle and reuse
Concrete is made from natural materials and is 100 % recyclable. Crushed concrete can be recycled as aggregates in new concrete or be used in the base course in road construction.
Crushed concrete also absorbs carbon dioxide at a faster rate than new concrete..
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© 2019 International Institute for Sustainable Development
Published by the International Institute for Sustainable Development
Betong och klimat. En rapport om arbetet för klimatneutral betong.
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The decarbonization. Benefits of sectoral circular economy actions.
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Vägledning klimatförbättrad betong.
A sustainable future for the European cement and concrete industry. Technology assessment for full decarbonisation of the industry by 2050.
ETHZ & EPFL 2018, Auréliecc Favier, Catherine De Wolf, Karen Scrivener and Guillaume Habert.
Team Thomas is actively contributing to building a sustainable society.
Over the years, Thomas Concrete Group has focused on reducing the climate impact of concrete.
Thomas Betong, our subsidiary, was the first company in Sweden, back in 2012, to offer its customers concrete products with a significantly reduced CO2 footprint. Thomagrön® is now an established product that delivers a reduction in climate impact of up to 50 %. In 2016 Thomas Miljöstomme® was launched, a completely unique building system with a demonstrated 30 % reduction in its carbon footprint.
We offer EPDs for products and projects to increase transparency and give our customers and the industry the opportunity to make more sustainable choices. We also work proactively with material suppliers and request EPDs for our raw materials.
Our ambition is to be an industry leader in providing sustainable products and services. We are working to reduce our environmental impact and increase the material’s service life, function, and performance. We are driving the development towards climate-neutral concrete. We are The Concrete Specialists.