Concrete Built the Modern World: Can We Reinvent It?

Concrete is the stuff used to build roads, bridges, and apartment buildings.

We make about 30 billion tonnes of it every year, more than any other material in the world.

Making concrete also creates a lot of greenhouse gases, which trap heat and warm up the planet.

In fact, if concrete were a country, it would be one of the biggest polluters on Earth.

Most of the pollution comes from cement, the glue that holds concrete together.

To make cement, limestone is baked in giant ovens at very high temperatures, and that baking releases carbon dioxide.

Scientists and builders are inventing new recipes for concrete that pollute less.

Some mix in waste materials from factories and farms, like fly ash, rice husk ash, and slag, instead of so much cement.

These new recipes can cut pollution by up to 40 percent while keeping the concrete just as strong.