Scientists have discovered a method to recycle cement from demolished concrete buildings.
Cement, the most commonly used construction material globally, is a significant source of greenhouse gas emissions due to the chemical reactions involved in heating limestone to high temperatures by burning fossil fuels. Recycling cement could greatly reduce its carbon footprint.
Researchers suggest that using electric-powered furnaces and renewable energy sources like wind and solar, instead of fossil fuels, could eliminate greenhouse gas emissions entirely.
This would be a substantial achievement since cement is fundamental to modern infrastructure and is the second most consumed material on the planet after water.
However, its production is a major contributor to climate change. If cement production were a country, it would be the third-largest emitter of CO2, responsible for 7.5% of human-made emissions.
The primary issue lies in the polluting chemistry of cement, which involves heating limestone to up to 1600 degrees Celsius in large kilns powered by fossil fuels.
This process not only emits CO2 from the fuel but also from the limestone itself, resulting in approximately one tonne of CO2 produced for every tonne of cement.
A team of scientists from Cambridge University has devised a method to bypass these emissions. They found that used cement can be reactivated by exposing it to high temperatures again, a well-established process in cement kilns.
The innovation lies in utilizing the heat generated by another heavy industry: steel recycling. In steel recycling, chemicals are added to molten metal to prevent it from reacting with air and forming impurities, creating a by-product known as slag.
The Cambridge team noticed that the composition of used cement closely matches that of the slag used in electric arc furnaces. This insight allows the reactivation of cement by piggybacking on the heat from steel recycling, offering a sustainable solution to cement’s carbon problem.
Researchers have been testing the new process at a small-scale electric arc furnace at the Materials Processing Institute in Middlesbrough. The BBC witnessed the production of the first high-grade, or “Portland,” cement during this trial. The team has dubbed it “electric cement,” marking a world-first achievement.
Lead scientist Cyrille Dunant explained to the BBC that this breakthrough could facilitate the production of zero-carbon cement.
“We have demonstrated that the high temperatures in the furnace reactivate the old cement.
Since electric arc furnaces utilize electricity, they can be powered by renewable energy, fully decarbonizing the cement-making process,”
Dunant also noted that this method reduces the pollution associated with steel recycling, as producing the chemicals currently used as slag has a high carbon cost.
Mark Miodownik, Professor of Materials and Society at University College London, praised the Cambridge team’s innovative combination of cement and steel recycling as “genius.” He believes that if the process can be scaled profitably, it could significantly reduce emissions. “Can it compete against the existing infrastructure that unsustainably continues to produce cement?” he asks. “Cement is already a billion-dollar industry. This is a David and Goliath situation.”
The hope is that electric cement will be cheaper to manufacture since it utilizes what is essentially waste heat from the steel recycling process. This week, Spanish company Celsa will attempt to replicate the process in its full-scale electric arc furnace in Cardiff.
The Cambridge team estimates that their low-carbon cement could meet up to a quarter of the UK’s demand, based on current rates of steel recycling. As the use of electric arc furnaces is expected to rise, the production of “electric cement” could also increase. Moreover, this process could be adopted worldwide, potentially leading to a dramatic reduction in cement emissions globally.
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HeadlineNew way of recycling cement could cut emissions , scientists say
Short HeadlineNew way of recycling cement could cut emissions
StandfirstCambridge University scientists developed recycled cement using heat which could cut emissions
Scientists have discovered a method to recycle cement from demolished concrete buildings.
Cement, the most commonly used construction material globally, is a significant source of greenhouse gas emissions due to the chemical reactions involved in heating limestone to high temperatures by burning fossil fuels. Recycling cement could greatly reduce its carbon footprint.
Researchers suggest that using electric-powered furnaces and renewable energy sources like wind and solar, instead of fossil fuels, could eliminate greenhouse gas emissions entirely.
This would be a substantial achievement since cement is fundamental to modern infrastructure and is the second most consumed material on the planet after water.
However, its production is a major contributor to climate change. If cement production were a country, it would be the third-largest emitter of CO2, responsible for 7.5% of human-made emissions.
The primary issue lies in the polluting chemistry of cement, which involves heating limestone to up to 1600 degrees Celsius in large kilns powered by fossil fuels.
This process not only emits CO2 from the fuel but also from the limestone itself, resulting in approximately one tonne of CO2 produced for every tonne of cement.
A team of scientists from Cambridge University has devised a method to bypass these emissions. They found that used cement can be reactivated by exposing it to high temperatures again, a well-established process in cement kilns.
The innovation lies in utilizing the heat generated by another heavy industry: steel recycling. In steel recycling, chemicals are added to molten metal to prevent it from reacting with air and forming impurities, creating a by-product known as slag.
The Cambridge team noticed that the composition of used cement closely matches that of the slag used in electric arc furnaces. This insight allows the reactivation of cement by piggybacking on the heat from steel recycling, offering a sustainable solution to cement’s carbon problem.
Researchers have been testing the new process at a small-scale electric arc furnace at the Materials Processing Institute in Middlesbrough. The BBC witnessed the production of the first high-grade, or “Portland,” cement during this trial. The team has dubbed it “electric cement,” marking a world-first achievement.
Lead scientist Cyrille Dunant explained to the BBC that this breakthrough could facilitate the production of zero-carbon cement.
“We have demonstrated that the high temperatures in the furnace reactivate the old cement.
Since electric arc furnaces utilize electricity, they can be powered by renewable energy, fully decarbonizing the cement-making process,”
Dunant also noted that this method reduces the pollution associated with steel recycling, as producing the chemicals currently used as slag has a high carbon cost.
Mark Miodownik, Professor of Materials and Society at University College London, praised the Cambridge team’s innovative combination of cement and steel recycling as “genius.” He believes that if the process can be scaled profitably, it could significantly reduce emissions. “Can it compete against the existing infrastructure that unsustainably continues to produce cement?” he asks. “Cement is already a billion-dollar industry. This is a David and Goliath situation.”
The hope is that electric cement will be cheaper to manufacture since it utilizes what is essentially waste heat from the steel recycling process. This week, Spanish company Celsa will attempt to replicate the process in its full-scale electric arc furnace in Cardiff.
The Cambridge team estimates that their low-carbon cement could meet up to a quarter of the UK’s demand, based on current rates of steel recycling. As the use of electric arc furnaces is expected to rise, the production of “electric cement” could also increase. Moreover, this process could be adopted worldwide, potentially leading to a dramatic reduction in cement emissions globally.
