Moving Toward a More Eco-Friendly Cement

Second only to water, concrete is the earth’s most highly utilized material. It’s estimated that on a global scale, we use more than 25 billion tons of new concrete annually, more than three tons of concrete per person. As China, India and other countries continue to industrialize, global use of concrete will only grow.

Why does this matter?

Because the manufacturing of cement, concrete’s main binding ingredient, accounts for an estimated 5% to 8% of the global carbon dioxide (CO₂) emissions attributed to human activity, which may be a factor contributing to global climate change.

Carbon dioxide is emitted at several points throughout the cement manufacturing process. First, there’s the energy consumed to quarry limestone, a primary component of cement, and get it to the cement manufacturing plant.

Once at the plant, limestone is crushed and mixed with other materials, such as clay, and the mix is heated in a kiln to roughly 2,700 degrees Fahrenheit (about 1,480 degrees Celsius). Along the way, the limestone breaks down in a chemical reaction called “calcination,” which releases CO₂.

The process produces both direct and indirect CO₂ emissions. Industry estimates attribute roughly 50% to 60% of a cement plant’s CO₂ emissions directly to the chemical reaction of calcination itself. Most of the rest, roughly 30% to 40%, comes from the fossil fuels burned to fire the kilns and produce the necessary heat.

Since concrete continues to be a central component in construction projects around the world, the search is on to find a way to make it a more eco-friendly material.

Growing Options to Reduce the Carbon Footprint of Cement

With significant impact comes significant opportunity. Because cement manufacturing is a major contributor to worldwide CO₂ emissions, beneficial changes to the manufacturing process could reduce those emissions appreciably.

Three key points of opportunity exist to reduce CO₂ emissions:

1. Reduce the indirect emissions by reducing the fossil fuels needed for firing up the kilns to process the limestone mixtures.
2. Reduce the direct emissions from the calcination process, generally by reducing the amount of limestone needed or otherwise revising the recipe of the mixture going through the calcination.
3. Use carbon capture and storage (CCS) approaches to trap the CO₂ that is emitted, either directly or indirectly, from the cement manufacturing process.

Commercial enterprises and academic institutions alike have been devising creative ways to reduce cement’s carbon footprint. They are looking both to nature and to antiquity for new ideas. Here are some of the most promising, as of this article’s 2015 publication:

• Calera, a California company, seeks to take the CO₂ emitted from other industries and turn these emissions into source material for concrete, thereby replacing the limestone. This process, modeled after how nature creates coral reefs, filters the collected CO₂ emissions through seawater. The result is a chalky material that can be used as a concrete ingredient and that doesn’t require the extreme heat of limestone for processing.
  
• Greenstone cement: Researchers at Drexel University found evidence suggesting that some blocks in Egypt’s ancient pyramids were cast from an early form of concrete, rather than carved from solid stone. Inspired by the pyramids’ longevity, the researchers developed an alkali-activated cement made mostly from slag, an industrial byproduct, and limestone, using a process that doesn’t require heating. Drexel estimated that it cuts energy use and CO₂ by 97% compared with traditional Portland cement.
• MIT Research: Scientists at the Massachusetts Institute of Technology didn’t alter any ingredients in the cement recipe as a way of reducing direct CO₂ emissions. Instead, they tweaked the ratio of ingredients. Conventional cements have a calcium-to-silica ratio of about 1.7. The researchers found that a ratio of about 1.5 produced a stronger cement, and that using less calcium could also cut emissions. One of the researchers put the potential reduction as high as 60%.
  
• Ferrock™: Developed at the University of Arizona, this is a replacement for Portland cement. This new type of “cement” is made from steel dust, an industrial waste product. The process for converting steel dust into a binding ingredient that can replace the cement in concrete actually requires CO₂. As such, Ferrock absorbs CO₂ as it hardens instead of emitting it.

Can These Options Really Replace Traditional Cement?

It is one thing to discover ways of altering cement’s recipe of ingredients so as to reduce the carbon footprint of cement. But it is equally important to ask: Do these changes to the cement favorably impact the characteristics of the resulting concrete?

So far, the early results have been promising. Researchers at businesses and universities have been conducting tests of strength and durability, and some report that their new products yield a concrete that meets or exceeds the strength and durability characteristics of concrete made from the tried-and-true Portland cement.

Free Download – 4 Reasons Why Your Concrete Is Taking Forever to Dry

No matter how quickly the movers and shakers in the cement manufacturing industry shift society toward the use of more eco-friendly cement, we can expect some things to stay the same. The curing process for concrete (that is, the chemical reaction occurring as the cement and water mixture harden, forming the concrete) is still where the durability properties of the concrete are set.

In addition, even if new experimental concrete mixtures may someday suggest the use of new concrete moisture testing methods, the flooring installer’s need for an accurate picture of the slab’s moisture condition will remain unchanged. Information about moisture condition will always be critically important when deciding whether a concrete slab is ready for the finished floor.

In-situ relative humidity (RH) testing, with sensors like those in the Wagner Meters Rapid RH^® kits, is widely considered the most reliable concrete moisture test. Relying on other moisture tests alone can raise the risk of a serious flooring failure. Always remember: doing it right the first time not only makes good economic sense, it makes good eco-sense, too!

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Jason Spangler

Jason has 20+ years’ experience in sales and sales management in a spectrum of industries and has successfully launched a variety of products to the market, including the original Rapid RH® concrete moisture tests. He currently works with Wagner Meters as our Rapid RH® product sales manager.

Last updated on October 22nd, 2026