Giving a second life to construction materials after demolition, engineers at the University of São Paulo and Princeton have developed an approach for recycling cement waste into a sustainable, low-carbon alternative that is comparable in performance to the industry standard.

In addition to lowering the carbon intensity of the cement and concrete industry, the process could enable new uses for construction and demolition waste, of which concrete is a significant component. In 2018 in the United States, the total amount of construction and demolition waste was more than twice that of household waste.

“Construction waste typically ends up either in a landfill, or, if it’s recycled, will be used in low-grade applications such as in pavements or in soils,” said research leader Sérgio Angulo, a professor of Civil and Urban Construction Engineering at the University of São Paulo. “It’s exciting to show that we can, in fact, recycle this recovered cement waste into a high-quality application.”

In their paper, published in ACS Sustainable Chemistry & Engineering, the researchers demonstrated that mixtures containing up to 80% of this recycled cement were just as strong as conventional Portland cement by itself while generating a fraction of the carbon emissions. Portland cement is the most common binder used to create concrete, but its high carbon intensity is the main reason the cement and concrete industry is responsible for around 8% of global emissions.