By KiddieDaily Editors · 2026-06-29 · 3 min read · 1 source

A shot of carbon dioxide rewires how cement sets

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Close Breadcrumb MIT News A shot of carbon dioxide rewires how cement sets A shot of carbon dioxide rewires how cement sets New research reveals the chemical sequence triggered by CO₂ injection in cement paste, capturing a fleeting intermediate reaction for the first time using real-time Raman spectroscopy. Andrew Paul Laurent | MIT Concrete Sustainability Hub Publication Date: June 11, 2026 Press Inquiries Press Contact: Andrew Paul Laurent Email: alaurent@mit.edu Phone: 617-715-5104 MIT Concrete Sustainability Hub Close Caption: A confocal Raman microscope (left) tracks the chemical evolution of CO₂-injected cement paste samples over 24 hours; the custom stage's quartz window enables the laser to scan from below. Cement paste is the basis for fresh concrete, as pictured at right; CO₂-injected concrete is gaining commercial traction as a material that permanently stores carbon dioxide.

Credits: Photos: Courtesy of the researchers (left) and AdobeStock (right). Previous image Next image One September day, it started to snow inside MIT’s Pierce Laboratory.  Researchers depressurized a tank of liquid carbon dioxide (CO2), instantly freezing it and releasing solid flakes. These were blended into cement paste and pressed into discs roughly the size of a dime, each sealed with a thin layer of vegetable oil to keep water in and air out.

The team trained lasers on each, observing for the first time the transient chemical reaction that might explain why CO2-injected cement paste gains its strength faster. Injecting CO2 into cement products like concrete is one way to store it and keep it out of the atmosphere. The process has attracted commercial interest, with a growing number of companies offering CO2-injected concrete mixes.

But until now, the underlying cement chemistry hadn't been directly visualized. A new open-access paper in the Journal of the American Ceramic Society — led by Associate Professor Admir Masic and first-authored by graduate student Marcin Hajduczek, both of the MIT Concrete Sustainability Hub and MIT Department of Civil and Environmental Engineering — describes the chemical sequence that unfolds after CO2 meets fresh cement paste. Co-authors include MIT colleagues Santiago El Awad and Franz-Josef Ulm, alongside researchers from IIT Jodhpur and CarbonCure Technologies.

Previous studies had pieced together a story about CO2 injection’s chemical impacts from theory and indirect evidence; the key reactions simply moved too fast, and vanished too completely, for conventional techniques to catch them in the act. Raman confocal microscopy could — and it works on a simple principle: Illuminate a molecule with a laser, and the scattered light will reveal its identity. The light interacts with each material’s unique chemical bonds, shifting in energy to produce a distinct spectral “fingerprint.” Even the most fleeting and amorphous phases leave a readable trace.

“We’ve used Raman spectroscopy to better understand some of the most interesting materials in history, from the Dead Sea Scrolls to Ancient Roman concrete,” says Masic. “Cement paste may seem less glamorous in comparison, but pointing a laser at CO2-injected cement paste as it hardens allows us to visualize things that haven’t been seen before.” What they saw, unfolding during 24 hours of continuous scanning, was a three-act chemical drama.

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