Concrete is strong and durable – which is why it’s the basis for so much of our infrastructure. It’s also terrible for the planet, due to one key ingredient: cement, which is responsible for almost 90% of concrete emissions. Researchers have now found a way to recover old cement while also reducing the environmental impact of recycling steel. Madeleine Finlay speaks to Julian Allwood, professor of engineering and the environment at the University Of Cambridge, to find out how the process works, and what it could mean for the emissions generated by the construction industry. Help support our independent journalism at theguardian.com/sciencepod