Among the myriad steps needed to clean up construction, a cement made with heated clay stands out.

The Argos plant in Rioclaro, Colombia, can churn out as much as 2.3 million tons of cement a year, used to build everything from dams and bridges to skyscrapers and stadiums. That has helped make Argos the biggest cement maker in Colombia—but also a major producer of carbon-dioxide emissions.

The cement and CO2 had been pouring out of Rioclaro nonstop for more than 20 years when the chief executive of Argos met an academic named Karen Scrivener, who had a simple pitch: change the recipe for cement to incorporate clay, and slash the carbon footprint. She called it LC3, or limestone calcined clay cement.

After four years of development, the revamped facility in Rioclaro went online this year, using clay that’s mined about 10 miles away and processed in a newly built kiln. Argos says the technology cuts energy consumption by 30% and reduces carbon output by almost half.