To clean up some of the pollution stemming from its supply chain and data centers, Microsoft is experimenting with new kinds of concrete.

Cement, a key ingredient in concrete, happens to be a big culprit in climate change. It’s responsible for around 8 percent of carbon dioxide emissions globally. Avoiding that pollution is no easy task, especially since concrete is the most widely consumed material in the world after water. A host of startups are looking for just the right recipe to make concrete minus the carbon dioxide emissions. And Microsoft wants to be a buyer.

“Something that we can do right now and we are doing right now is shopping around. You know, concrete supplier A might have lower embodied carbon [emissions] than concrete supplier B,” Sean James, senior director of data center research at Microsoft, tells The Verge. “We believe that the data center industry can then lead the rest of the construction industry in adopting these things.”

In Quincy, Washington, Microsoft is testing out futuristic concrete mixes that it hopes will result in half as much carbon dioxide emissions as traditional concrete. This January, outside of one of its data centers, it poured different kinds of mixes out to harden into concrete slabs as part of the pilot project. They’ll observe the slabs over the next several months to see how they might fare if used to construct data centers in the future.

Typically, cement is made by firing up a kiln filled with limestone and other materials. The process creates carbon dioxide emissions in two ways: through the energy burned to heat the kiln, and through a chemical reaction that happens when heating up limestone.

In Quincy, Microsoft is trying out a couple of different strategies for reducing those emissions. One concrete mix is made with fly ash from coal companies and other kinds of industrial waste. The hope is that the team won’t have to use as much carbon-intensive cement in the mix by adding the industrial waste as an ingredient.

The second mix used in Quincy grew out of an idea a University of Colorado Boulder professor, Wil Srubar, got after snorkeling on his honeymoon. Reefs are made up of limestone produced by coral and algae. Algae actually captures CO2 in the process, so what if it could be put to work making limestone for cement? Srubar co-founded the startup Minus Materials, which is trying to commercialize the process and is supplying Microsoft with its limestone.

Similar projects are underway with concrete suppliers in Des Moines, Iowa, and San Antonio, Texas, according to Microsoft. The company’s Climate Innovation Fund has also invested in other startups developing low-carbon concrete and building materials.

Microsoft doesn’t know yet when and if these materials will be ready to become the building blocks of its data centers. And even if they do pass the test, the bulk of a data center’s carbon emissions still comes from all the energy its servers use.

But if the pilot is successful, it could help Microsoft tackle pollution from at least one link in its supply chain. Microsoft has pledged to become carbon negative by 2030, meaning it plans to take more CO2 out of the atmosphere than it releases as a company. And yet, while Microsoft tries to rein in its greenhouse gas emissions, a Verge investigation earlier this year found that many of its suppliers’ emissions continue to grow.