Brief
According to data from the United Nations Environment Programme, the production of concrete is the source of 8 per cent of humanity’s carbon dioxide emissions. If the global concrete industry were a country, it would be the third-largest carbon dioxide emitter, surpassed only by China and the United States.
Insight
Concrete is the single most abundant human-made material on Earth. It’s most likely beneath you right now.Some 70 per cent of the world’s population lives in a building made with concrete. Every year – and year after year – the world produces enough concrete to pave over the Great Lakes.
But concrete is also catastrophic for the environment.
According to data from the United Nations Environment Programme, the production of concrete is the source of 8 per cent of humanity’s carbon dioxide emissions. If the global concrete industry were a country, it would be the third-largest carbon dioxide emitter, surpassed only by China and the United States.
But what if, rather than releasing carbon dioxide into the atmosphere, concrete absorbed it instead?
One Canadian technology company has produced an alternative concrete that does exactly that.To make this special blend, “you get rid of the cement,” says Chris Stern, chief executive officer of Montreal-based Carbicrete.
Most of concrete’s carbon dioxide emissions come from manufacturing its binding agent cement. This process involves heating limestone to 1,400 C, generally using a fossil-fuel source. The heat causes the limestone to break down and release another dose of carbon dioxide.Over the next four decades, the equivalent of 500 New York Cities will be built around the world.
— 2020 Global Status Report for Buildings and Construction, United Nations
The product Carbicrete, on the other hand, uses steel slag, a waste material from the steel-making process, to replace cement as a binding ingredient. The slag is injected with carbon dioxide captured from industrial plants. The curing process converts the carbon dioxide into a mineral; not a trace of it remains.
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![Why Use Recycled CO2 in Fresh Concrete? Download PDF Copy Reginald Davey By Reginald DaveyNov 29 2022 Decarbonizing the construction industry is currently a central research focus. Engineers and scientists have extensively explored innovative strategies to reduce carbon emissions and consequent climate change-inducing characteristics of materials and processes. recycled co2, co2 in concrete, decarbonisation Image Credit: Olena Sergeyeva/Shutterstock.com This article will provide an overview of current strategies being employed in the construction sector, and will explore an innovative approach: utilizing recycled carbon dioxide in fresh concrete, the most commonly utilized building material today. Why is Decarbonizing the Construction Industry Important? Industrial activity and population growth have been intrinsically linked to climate change over the past few decades, with growing evidence that human activity is causing global temperature rises, increasingly extreme weather events, and accelerating biodiversity loss. The global construction and building sector is the biggest consumer of raw materials and is responsible for around 25-40% of the total carbon dioxide emissions worldwide. This is in large part driven by rapid industrialization and urbanization in emerging economies such as China and India. There exists significant potential for decarbonizing construction, an essential industry that provides infrastructure and domestic and commercial buildings. With the world warming at an alarming rate, there is no space for the industry’s current business-as-usual approach to continue, and innovative decarbonization strategies have been explored in recent years. Cement and Concrete Production: A Key Driver of Carbon Emissions in the Sector Cement and concrete manufacture are major contributors to the construction industry’s CO2 emissions. Responsible for around 7-8% of total emissions, the global cement industry has more than tripled its emissions in the past three decades as cement production has increased in intensity to meet global demands. More than four billion tonnes of cement are produced and consumed per year globally. Producing this critical construction material requires the use of limestone, which is heated to yield calcium oxide, otherwise known as lime. This process emits considerable amounts of carbon dioxide. Moving cement and concrete manufacture away from its current linear model to a model more in line with the aims of the circular economy is a key research focus currently. Globally, engineers, companies, and architects are increasingly embracing the circular economy as a central element of the construction industry. Cement and Concrete Decarbonization Strategies Innovations in building material design and processing are improving the sustainability of concrete. Multiple innovative strategies have been implemented in research and test projects recently and are increasingly being applied in real-world applications in several countries. Waste materials from various industrial processes have been incorporated into sustainable concrete to reduce the amount of virgin resources needed in its production. This approach has the additional benefit of reusing waste resources from industries such as steelmaking or the construction sector itself which would otherwise be disposed of in landfills or incinerated. Related Stories How Has Concrete Changed Over Time? U.S. Concrete Acquires Ready-Mixed Concrete Assets and Property of Diamond Concrete US Concrete Introduces Ready Mix Concrete Solution for Covering Concrete Floor Failures Image Credit: Evannovostro/Shutterstock.com Another approach recently investigated is the inclusion of carbonaceous nanomaterials such as graphene in concrete. This strategy helps to enhance the mechanical properties of concrete, reducing the amount needed in building projects and therefore improving its carbon footprint. This produces a material known as Concretene, which has been used in a gym in Amesbury in the UK. Buildings also have a significant amount of embedded carbon, which is lost when they are demolished. Repurposing waste concrete from demolition is a common approach to producing recycled concrete aggregate that can be reused. However, due to its low quality, it is commonly used in applications such as new roads, which does not adequately satisfy the circular economy aims of the construction sector. Utilizing Concrete as a Carbon Sink: An Innovative Approach to Decarbonization An intense focus has been placed in recent years on mitigating the climate change-inducing effects of industrial carbon dioxide emissions by capturing and sequestering them. This has led to widespread research on carbon capture and storage (CCS) technologies. But what if concrete and cement could become carbon sinks? This is the aim of CarbonCure, a company based in Halifax, Canada. Their technological solutions introduce recycled CO2 into fresh concrete. This recycled CO2 reacts with calcium in raw mixtures to produce calcium carbonate, reducing the need for raw materials and intense carbon dioxide-emitting manufacturing processes. The company’s innovative carbon dioxide-injecting technology can be used with both fresh concrete and recycled concrete aggregates without compromising the final product’s quality. The CO2 becomes mineralized and permanently embedded in the mixture and provides both environmental and economic benefits for concrete manufacturers. The technology can be easily installed in current concrete plants with no upfront capital investment, decreases further operational costs, and improves the sustainability of concrete production. Once injected, it enhances properties such as compressive strength, which reduces the need for cement while maintaining strength requirements. CarbonCure’s technology consists of two main elements: A control box and a valve box. The valve box connects to a tank containing the recycled CO2, delivering a controlled flow of carbon dioxide into the concrete mix. Real-time control and data analysis are provided by the system’s control box. Seamless software integration makes this a highly efficient system with no negative effects on batching and loading time. This sequestered CO2 is permanently removed from the environment and is not released even when the building is demolished. CarbonCure’s solution can be used for every residential and commercial application, reducing the amount of cement needed in a building project and helping the construction sector to achieve its net zero and circular economy aims. In Summary Anthropogenic climate change and the increasing damage to the natural environment require innovative decarbonization solutions in industrial sectors such as construction. Many approaches have been explored in recent decades, and with technologies such as CarbonCure’s system, the construction industry can benefit from the ability to make new buildings into carbon sinks that remove emissions from the environment. More from AZoBuild: Cleaner Construction with Carbon-Negative Algae-Grown Limestone References and Further Reading Sanderson, K (2022) The path towards more-sustainable building construction [online] nature.com. Available at: https://www.nature.com/articles/d41586-022-03650-3 Carboncure.com (website) Available at: https://www.carboncure.com/ Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website. Reginald Davey Written by Reginald Davey Reg Davey is a freelance copywriter and editor based in Nottingham in the United Kingdom. Writing for AZoNetwork represents the coming together of various interests and fields he has been interested and involved in over the years, including Microbiology, Biomedical Sciences, and Environmental Science. Download PDF Copy Citations Tell Us What You Think Do you have a review, update or anything you would like to add to this article? 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