A new method to produce low-emission concrete at scale has been created

University of Cambridge’s researchers have developed a way to create very low-emission concrete at scale. This breakthrough has the potential to revolutionize the shift towards net zero emissions.

The technique, dubbed “an absolute miracle” by the researchers, recycles cement while also recycling steel using electrically powered arc furnaces. After water, concrete is the second most used substance on Earth and contributes roughly 7.5% of all anthropogenic CO2 emissions. One of the major issues in the worldwide decarbonization process is finding a scalable and economically viable method to reduce emissions from concrete while fulfilling demand.

The researchers from the University of Cambridge discovered that lime flux, often used to eliminate impurities from steel recycling and ends up as waste, can be effectively replaced with old cement. However, recycled cement that can be utilized to create fresh concrete is what’s left behind when used cement is substituted for lime.

Since less lime flux is required, the cement recycling technique created by the Cambridge researchers and published in the journal Nature dramatically lowers emissions from both steel and concrete without having to add high costs. For the first time, low-emission concrete at scale can be produced in an electric arc furnace (EAF), according to recent tests conducted by the project partner Materials Processing Institute. Eventually, if the EAF was driven by renewable energy, this process could result in cement with zero emissions.

“We held a series of workshops with members of the construction industry on how we could reduce emissions from the sector,” said Cambridge’s Department of Engineering Professor Julian Allwood in regards to low-emission concrete at scale. “Lots of great ideas came out of those discussions, but one thing they couldn’t or wouldn’t consider was a world without cement.”

Scientists have been looking at cement substitutes for the last ten years and have discovered that fly ash and other alternative materials can replace around half of the cement within concrete. However, for the substitutes to solidify, the remaining cement must chemically activate them.

“It’s also a question of volume,” Allwood added. “We don’t physically have enough of these alternatives to keep up with global cement demand, which is roughly four billion tonnes per year. We’ve already identified the low hanging fruit that helps us use less cement by careful mixing and blending, but to get all the way to zero emissions, we need to start thinking outside the box.”

According to the researchers, the Cambridge Electric Cement process has been scaling up quickly. By 2050, it may produce one billion tons of low-emission concrete at scale annually, or almost a fourth of the world’s current yearly production of cement.

“As well as being a breakthrough for the construction industry, we hope that Cambridge Electric Cement will also be a flag to help the government recognize that the opportunities for innovation on our journey to zero emissions extend far beyond the energy sector,” stated Allwood.