For years, companies have injected carbon dioxide into concrete to trap emissions and improve early performance. The construction industry embraced the approach even though researchers could not fully explain why it worked. Now, scientists at MIT say they have finally watched the chemistry unfold in real time.

Using laser-based imaging, the team captured the rapid reactions that occur when carbon dioxide meets fresh cement paste. The observations revealed a temporary chemical pathway that reshapes how the material hardens. The process produces a more evenly distributed binding structure and boosts early strength.

The findings could help engineers fine-tune low-carbon concrete technologies already entering the market across the United States. The work also offers a clearer picture of how cement, one of the world’s most carbon-intensive materials, can store captured carbon while maintaining performance.

Tracking hidden reactions

Researchers from MIT’s Concrete Sustainability Hub and Department of Civil and Environmental Engineering used Raman confocal microscopy to monitor cement samples continuously during their first 24 hours of curing. The technique identifies materials by analyzing how laser light interacts with chemical bonds. Each compound leaves behind a distinct spectral signature.

Previous studies relied largely on theory and indirect measurements because the reactions happened too quickly for conventional tools to detect. “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,” Associate Professor Admir Masic said.

“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.” The team discovered that carbon dioxide initially captures calcium released during cement dissolution. That temporary shift slows normal hydration and changes the environment inside the paste.

The disappearing template

As calcium becomes tied up, dissolved silicates spread through the material and assemble into an interconnected silica gel network. The gel survives only briefly.

Once the injected carbon dioxide fully mineralizes several hours later, standard hydration resumes. Calcium hydroxide forms and immediately reacts with the silica network. That reaction produces calcium silicate hydrate, or C-S-H, the compound responsible for cement’s binding strength.

Unlike conventional cement, however, this new C-S-H develops throughout the material rather than clustering around cement particles. “At first, the fleeting nature of the silica gel looked like a fluke in the Raman data,” graduate student Marcin Hajduczek said.

“But it quickly became clear that its sudden disappearance was a consistent, undeniable feature of every CO2-injected sample.” Stronger concrete, new possibilities

The altered pathway leaves behind a more uniform internal structure. In tests, cement paste containing carbon dioxide equal to 1 percent of cement weight achieved an average of 13 percent higher compressive strength after 24 hours than reference samples.

The findings also challenge previous assumptions. Researchers found calcium carbonate particles acted more like spectators than drivers of strength development. “We’ve been injecting CO2 into cement products for years without fully understanding what it was doing inside,” Masic said.

“Now that we understand the mechanism behind the improved performance, we can start to control it.” The researchers caution that dosage remains critical. Excessive carbon dioxide can lock away too much calcium and disrupt beneficial reactions. Even so, the work offers engineers a roadmap for designing stronger, lower-carbon cement products for future infrastructure projects.

The study is published in the Journal of the American Ceramic Society.

Autonomous aircraft are increasingly drawing attention as the U.S. military looks for new ways to sustain operations in contested and hard-to-reach environments. Pyka’s latest demonstration suggests those efforts may be moving beyond theory and closer to operational reality.

The California-based company has introduced a precision airdrop capability for its DropShip autonomous aircraft, enabling it to deliver critical supplies without a pilot onboard. Pyka says the system could help U.S. and allied forces move mission-essential cargo across long distances when traditional supply routes become disrupted or unavailable.

The demonstration reflects a broader shift in military logistics planning. Defense leaders have warned that future conflicts may challenge access to established transportation networks, creating demand for flexible and autonomous alternatives.

During a recent test flight, DropShip released multiple 200-pound payloads from an altitude of 300 feet. The cargo landed within roughly 50 feet of the intended target area, according to the company.

Built for denied environments

DropShip was designed as a heavy-lift autonomous platform capable of operating where conventional logistics networks cannot. The hybrid-powered aircraft has a maximum takeoff weight of 1,600 pounds and can carry up to 650 pounds of usable payload. It requires only 550 feet of runway to launch with a full payload.

Pyka says the aircraft can support same-day delivery missions across a 2,000-mile operational radius. It offers a ferry range of up to 3,500 miles and can travel more than 1,000 miles while transporting 500 pounds of cargo. The aircraft cruises at 75 knots and can sprint at 90 knots. It can also operate at service ceilings of up to 20,000 feet mean sea level.

Rapid development pace

The precision airdrop test represents another milestone in what has been a compressed development schedule. Pyka said DropShip completed its maiden flight just six months after the program launched. The aircraft progressed from first flight to autonomous precision airdrop capability within eight months.

The company credited that pace to the core technology stack already powering its commercial aircraft. Engineers adapted existing autonomous systems to speed development and testing.

Expanding mission options

Pyka believes the aircraft could play a role in a variety of missions beyond cargo transport. “Until now, there hasn’t been a safe, economical, or practical way to autonomously deliver critical supplies directly to a specific location hundreds or even thousands of miles away,” Michael Norcia, Pyka’s CEO and co-founder, said.

Norcia said operators could use the aircraft to transport fuel, water, medical supplies, repair parts, and other mission-essential cargo exactly where it is needed. He added that the capability could change logistics operations in remote regions, disaster zones, and contested environments where access remains limited.

Beyond cargo delivery, DropShip can support intelligence, surveillance, and reconnaissance missions, communications support, and expeditionary power applications. The aircraft also features a reconfigurable mission computer designed to accommodate evolving operational needs.

Pyka plans to continue expanding the aircraft’s flight envelope ahead of customer evaluations and operational exercises with the U.S. government later this year.

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Oklo has moved one step closer to bringing its first advanced reactor online after securing another key federal approval. The milestone advances the company’s efforts to demonstrate that next-generation nuclear plants can move from concept to deployment under existing government oversight.

The U.S. Department of Energy’s Idaho Operations Office has approved the Preliminary Documented Safety Analysis for Oklo’s Aurora powerhouse at Idaho National Laboratory. The decision pushes the project further through the Department of Energy’s Reactor Pilot Program, which aims to accelerate advanced reactor deployment while maintaining rigorous safety reviews.

For Oklo, the approval represents more than a regulatory checkpoint. It also provides momentum for a technology that supporters believe could strengthen America’s future energy mix and domestic industrial capacity.

Building toward deployment

The approved safety analysis establishes Aurora-INL’s preliminary safety basis. It evaluates potential hazards, accident scenarios, safety controls, and major design commitments that will guide the project through its next stages.

“This approval represents an important milestone for Aurora-INL and helps establish a foundation for future Aurora deployments,” said Jacob DeWitte, Oklo’s co-founder and chief executive officer. He added that the Idaho project is demonstrating how advanced reactors can progress through real-world safety reviews, construction activities, and eventually commercial licensing.

Aurora-INL will be the first of Oklo’s planned fast fission power plants. The project has steadily advanced since 2019, when the company received a site-use permit at Idaho National Laboratory and later secured access to recovered fuel from the Experimental Breeder Reactor-II through a competitive DOE process.

Oklo also received approval to begin site characterization work at the Idaho site in November 2024. Those activities helped prepare the groundwork for future construction and deployment efforts.

Reactor with historic roots

Aurora differs from traditional nuclear plants through its fast neutron reactor design and compact architecture. The system uses heat pipes to move heat away from the reactor core and into a supercritical carbon dioxide power conversion system that generates electricity.

The reactor builds on operating experience from the Experimental Breeder Reactor-II, which operated in Idaho between 1964 and 1994. Oklo says Aurora uses metallic fuel to provide both electricity and usable heat while offering greater operational flexibility.

The design can operate using either fresh high-assay low-enriched uranium, known as HALEU, or recycled fuel derived from used nuclear material. That capability has attracted attention as the United States seeks reliable, carbon-free energy sources to support growing electricity demand.

Expanding fuel strategy

Aurora’s progress comes as Oklo works to secure multiple fuel pathways for future reactor deployments. The company is developing the Aurora Fuel Fabrication Facility in Idaho, where it plans to produce the initial fuel assemblies for Aurora-INL using material recovered from EBR-II.

The Department of Energy approved the facility’s preliminary safety analysis in late 2025. That decision made A3F the first project authorized under the agency’s Fuel Line Pilot Program.

Oklo also entered advanced negotiations last month under the Department of Energy’s Surplus Plutonium Utilization Program. The initiative aims to make designated surplus plutonium available for conversion into reactor fuel under strict security and safeguards requirements.