Manufacturing a cubic yard of traditional concrete emits about 400 pounds of carbon dioxide, a greenhouse gas that adds to the overall warming of the planet, according to the Portland Cement Association

Cement's emissions intensity comes from the high heat required to make it. Limestone is baked in a kiln reaching temperatures up to 2,500 degrees Fahrenheit to produce clinker, or compact balls of minerals. The clinker is later mixed with gypsum to form the raw material concrete companies need.

That process, according to a report from the Environmental Protection Agency, produces 1 metric ton of CO. Carbon dioxide is the most prominent greenhouse gas emitted into the atmosphere, and its heat-trapping power has accelerated global temperatures and climate change.