Almost all of us interact with concrete on a daily basis. It’s used for sidewalks and roads, buildings, floors, countertops, and even sculpture. Concrete is known for its resistance to rotting or rusting and can withstand seawater, abrasion, and freeze-thaw cycles for decades. It’s also infamous for its contribution to climate change. Let's talk about it.
Putting Concrete in Context
Concrete is a core part of modern architecture, landscape, and design. Aside from structural elements and foundations, concrete is used in various aesthetic design elements. Swiss-French architect, designer, and painter Le Corbusier crafted a great example of how beautiful and durable material can be when shaped by a creative mind. His 1963 Complex du Capitole embraces brutalist concrete design, with concrete making up over 80% of the overall building material used during construction. Le Corbusier incorporated concrete in all aspects of this design from structure to flooring and wall finishes.
Since the late 19th century we have seen exponential growth in the use of concrete. On the surface, the widespread use of concrete seems like a great idea. It's a durable and cost-effective material that can be artful. However, its impact on the environment is a different story. Concrete has quickly become the most consumed material on the planet, second only to water. It even holds its own global CO2 emissions category separate from what we call, “Industry Emissions”, making up 8% of annual global CO2 emissions.
Concrete is created by mixing cement, which is composed of limestone, clay, and other minerals, with sand, gravel, and water. Cement production alone emits 600 kilograms of CO2 per ton - and 4.1 Billion metric tons of cement were produced in 2022. Concrete synthesis then uses fossil fuels to heat the mixture to 1,400°C in a kiln, which can produce even more emissions depending on the heat source.
The impact of concrete production on our environment is not negligible. Environmentalists, architects, and concrete manufacturers alike know that immediate change is necessary. So, what’s being done?
Reuse, Repurpose, Recycle
Repurposing concrete is labor intensive, but has the potential to make a significant impact on the overall reduction of CO2 emissions. Concrete rubble, known as urbanite, has the ability to be cut down into smaller slabs and bricks to be repurposed in various ways. Today we are using urbanite in retention walls, pathways, buildings and aesthetic finishes. Urbanite can also be seen as riprap, a loose aggregate used along shorelines to protect against erosion.
Industry Reform
The largest manufacturer of concrete globally, LafargeHolcim, published their Net Zero Pledge in 2023. This pledge outlines plans to drastically reduce the company's carbon footprint by 2030 and ultimately become carbon neutral by 2050.
“We are decarbonizing our operations by reducing our clinker factor, using alternative fuels and raw materials, and increasing our thermal substitution rate and renewable energy use.”
-Holcim Climate Action
What is the “clinker factor?” Clinker is an intermediary product created during the cement production process once the limestone has melded with other minerals like clay and calcium silica. The chemical reactions caused during this phase release the highest amount of carbon dioxide, which is why it’s become a focus of reduction efforts.
There are also smaller manufactures like New Jersey based start-up, Solidia Technologies, who are working hard to set the bar for a more environmentally sustainable industry standard. Solidia Technologies has been working hard to bring awareness to the impact of concrete emissions since 2007, and ultimately becoming their own manufacturer in 2011. Solidia Technologies has reformulated how the cement element of the concrete is produced, resulting in a product that creates 30-40% fewer emissions. They use captured CO2 emitted to cure the cement, allowing a portion of the emissions to become trapped inside of the final cured product. This method has the ability to reduce CO2 emissions by up to 60% in overall production.
While concrete remains a cornerstone of modern infrastructure and design, its environmental impact cannot be overlooked. As we navigate the dual challenge of meeting global construction demands and addressing climate change, it is imperative that the industry continues to explore reform and the reuse of materials. Innovative approaches, such as repurposing urbanite and adopting sustainable production methods, are crucial steps toward minimizing concrete's carbon footprint. Companies like LafargeHolcim and Solidia Technologies are leading the way, demonstrating that significant progress is achievable through commitment to sustainability.
By embracing these practices and prioritizing the circular economy, we can transform concrete from a major environmental concern into a sustainable resource, ensuring that this versatile material contributes positively to both our built environment and the planet. It's an exciting time in the industry - together, we can build a future that harmonizes durability, beauty, and ecological responsibility.
Alexa Walker
Sources:
“4 Ways to Make the Cement Industry More Sustainable.” World Economic Forum, 13 Sept. 2024, www.weforum.org/agenda/2024/09/cement-production-sustainable-concrete-co2-emissions/#:~:text=First%20by%20replacing%20half%20of,used%20instead%20of%20fossil%20fuels.
“Climate Action.” Sustainable Construction & Building Company | Holcim, 30 Apr. 2024, www.holcim.com/sustainability/climate-action.
Jean, Mélanie, and Mélanie Jean. “17 Major Concrete-consuming Businesses Pledge to Use 100% Net-zero Concrete by 2050 | WBCSD.” WBCSD, 13 Nov. 2023, www.wbcsd.org/news/17-major-concrete-consuming-businesses-pledge-to-use-100-net-zero-concrete-2050.
Just BioFiber | the Future of Building. justbiofiber.com.
Loiseau, Steven. “Complexe Du Capitole - Le Corbusier - World Heritage.” Le Corbusier - World Heritage, 15 June 2022, lecorbusier-worldheritage.org/en/complexe-du-capitole.
Mollard, Manon. “Concrete - the Architectural Review Issue 1515, October 2024.” The Architectural Review, 21 Oct. 2024, www.architectural-review.com/essays/letters-from-the-editor/ar-october-2024-concrete.
Solidia TechnologiesTM. “Cement Sustainability | Solidia TechnologiesTM.” Solidia TechnologiesTM | Making Sustainability Business as Usual, 27 Oct. 2023, www.solidiatech.com/sustainability.
Oluwafemi Ezekiel, Ige & Kallon, Daramy & Desai, Dawood. (2024). Carbon emissions mitigation methods for cement industry using a systems dynamics model. Clean Technologies and Environmental Policy. 26. 1-19. 10.1007/s10098-023-02683-0.
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