Concrete surrounds us in our cities and stretches across the land in a vast network of highways. It’s so ubiquitous that most of us take it for granted, but many aren’t aware that concrete’s key ingredient, ordinary portland cement, is a major producer of greenhouse gases.

Each year, manufacturers produce around 5 billion tons of portland cement — the gray powder that mixes with water to form the “glue” that holds concrete together.  Read More