Making cement usually means firing materials at punishing temperatures. A new study says there may be a lower-pollution way to do it.

In a paper published May 13 in ACS Energy Letters, researchers described an electricity-driven continuous reactor that converts limestone and silica into calcium silicate hydrate, or “eCSH.” That material can then be heated into belite, a key ingredient in cement clinker.

According to the study, the belite formed at 1,202 degrees Fahrenheit, well below the roughly 2,192 degrees Fahrenheit typically required in conventional production.

Cement manufacturing is highly energy-intensive because it depends on extreme heat, usually produced by burning coal and other fuels. The researchers said lowering the heat requirement could cut the fuel needed to make cement and reduce the carbon pollution tied to the process.

According to the study, the method could lower thermal demand by 70 percent and reduce carbon dioxide pollution by 98 percent compared with ordinary Portland cement clinker production.

For the process using waste cement, the paper said emissions were calculated at about 20 kilograms of CO2 per ton of belite-rich cement clinker, compared with roughly 800 kilograms per ton for standard clinker.

The team said the process can work with limestone and silica, and also with waste cement. That means old cement from demolished structures could potentially be used as feedstock for new cement production.

According to the paper, ordinary Portland cement clinker is composed mainly of alite, with belite also present. The authors said belite develops at lower temperatures than alite, though standard production still requires significant heat.

By first producing eCSH electrochemically, the researchers said they were able to make belite at much lower temperatures than usual.

The paper said the method “presents a credible path” to reducing the industry’s environmental footprint.

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