Carbon Dioxide Sequestration

Investment Analysis Clubs Macro Economic Trends and Risks
1

The most used construction material on the planet is concrete, which is cement mixed with aggregate of one kind or another.

From MIT labs:

Injecting carbon dioxide into cement is a growing commercial strategy to store CO₂ and reduce emissions. But until now, no one had directly observed what actually happens chemically when CO₂ meets fresh cement paste.

Using real-time Raman spectroscopy, MIT researchers, led by Associate Professor Admir Masic in the Department of Civil and Environmental Engineering, captured the fleeting chemical reactions for the first time. They discovered a three-stage process where CO₂ temporarily suppresses the paste’s alkalinity, creating a distributed silica gel network that ultimately produces a stronger, more uniform microstructure.

The result: CO₂-injected cement achieved 13 percent higher compressive strength at 24 hours compared to conventional mixes.

“Pointing a laser at CO₂-injected cement paste as it hardens allows us to visualize things that haven’t been seen before,” says Masic. The findings, published in the Journal of the American Ceramic Society, reveal the chemistry behind a technology already attracting commercial interest—and could help optimize it further.

9 Likes
2

Wikipedia: It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker, and then grinding the clinker with the addition of several percent (often around 5%) gypsum.

Heating limestone in a kiln should produce calcium oxide which hydrates to calcium hydroxide. You expect carbon dioxide to form calcium carbonate (limestone). No problem as long as the cured concrete retains its strength.

1 Like
3

I hope you are not implying this sequestration technique is some kind of solution to the rising atmospheric CO2 concentration. Even if this technique is universally adopted world-wide, the CO2 savings would be minuscule, at best.

From the MIT article in the original post:

"In the study, paste mixed with CO2 at 1 percent by cement weight achieved, on average, 13 percent higher compressive strength at 24 hours, compared to reference mixes."

So the CO2 takes up 1% by weight of the cement used to make the concrete. Every year, the world produces about 4.2 billion metric tonnes of cement. One percent of that is 42 million tonnes. That is about the same annual CO2 emissions as is emitted in the state of New Mexico.

With China emitting over 11,200 million tonnes of CO2 per year, a 42 million tonne savings is hardly more than a rounding error.

_ Pete

3 Likes
4

Another aspect is that the limestone charged to the kiln gives off carbon dioxide when calcined. Plus the kiln is usually fueled by fossil fuels.

Inject captured carbon dioxide into wet concrete may sequester carbon dioxide effectively but its doubtful it will absorb all the carbon dioxide released in the kiln.

I suppose electric kilns or hydrogen green kilns are possible but that might be next generation technology. Lots more wind, wave, solar, geothermal, nuclear investment required.

3 Likes
5

For those interested, here are more details about the role of CarbonCure Technologies, a Canadian company that provides concrete producers a drop-in solution that leverages carbon mineralization to reduce manufacturing costs and improve cement efficiency without changing performance.

I highly recommend first clicking the video at the following CarbonCure website that provides an excellent, macro overview and application of carbon mineralization in concrete.

https://www.carboncure.com

Background

SEPTEMBER 16, 2022

CarbonCure Statement on Passage of California’s Low Carbon Construction Bill

https://www.carboncure.com/news/carboncure-statement-on-passage-of-california-low-carbon-construction-bill/

The following is a statement from CarbonCure Technologies Senior Director of Customer Success Eric Dunford on California’s enactment of the Carbon Intensity of Construction and Building Materials Act (A.B. 2446):

“California Governor Gavin Newsom today signed A.B. 2446, the Carbon Intensity of Construction and Building Materials Act, directing the state of California to establish a process for achieving a 40 percent reduction in the carbon intensity of building materials for all public and private construction by 2035. This measure is a policy model for other states and a major step forward in reducing embodied carbon emissions generated by new construction and building materials. Fundamentally, this requirement will help create demand for low-carbon construction materials and accelerate industry adoption of best practices and technologies to reduce the carbon footprint of construction materials like concrete.

“CarbonCure is proud to have supported this sustainable transition, in California and across the U.S., offering our suite of hardware and software solutions for carbon removal and emissions reductions to benefit concrete producers, designers and builders. Our producer partners across the state of California are eager to supply the market with their high quality, lower carbon concrete products. And through policy making such as this, champions for sustainability in other states also have the opportunity to incentivize innovation in the construction sector and ensure a healthier environment and greener future for our children and our communities.”

JUNE 11, 2026

New Study Reveals How CO₂ Drives Early Strength Gains in Cement & Concrete at the Molecular Level

MIT’s Masic Lab and CarbonCure researchers have published first-of-its-kind, direct evidence of a novel hydration pathway in CO2-activated cement, providing new scientific validation of carbon mineralization in concrete.

https://www.carboncure.com/news/mit-study-with-carboncure-reveals-how-co2-mineralization-drives-improved-concrete-microstructure/

Cambridge, MA & Halifax, Nova Scotia, June 11, 2026 — A new peer-reviewed study, published in the Journal of the American Ceramic Society, has for the first time captured in real time the precise chemical mechanism by which CO2 injected during cement paste mixing enhances early hydration and produces a more evenly distributed, tightly-woven microstructure.

Co-authored by researchers at the Massachusetts Institute of Technology’s Masic Lab and CarbonCure Technologies, the team used advanced in situ Raman microspectroscopy—a technique capable of identifying individual chemical phases as they form at the micron scale, smaller than a human hair. Observing CO2-activated cement hydration unfold hour-by-hour over 24 hours, the researchers uncovered the molecular sequence behind the early strength enhancing effects of CO2 in cement, concrete’s key ingredient. Rather than disrupting the material’s chemistry, CO2 in early-stage hydration creates a tightly-linked binder microstructure.

Why This Matters for the Industry

For concrete producers, engineers and builders, this study provides a molecular-level explanation of how CO2 mineralization works in manufacturing, unlocking the opportunity to optimize concrete mix designs, reducing cement while protecting strength. It represents an important step toward production of lower carbon concrete to meet market demand while also delivering operational savings.

“The research findings provide the strongest experimental validation yet of carbon mineralization in concrete, explaining how carbon utilization technologies help producers reduce cement content and costs while delivering consistent, high-performing concrete,” said CarbonCure CEO Yuliya Kravtsov. “This science reaches far beyond a lab setting. It’s been commercially proven by our real-world, worldwide application across more than 11 million loads in projects ranging from residential construction to complex high rise developments and infrastructure builds.”

Commercial Application

Carbon utilization technologies represent one of the most commercially scalable, near-term pathways for reducing embodied carbon in the built environment. CarbonCure’s carbon mineralization systems are currently deployed at hundreds of concrete plants in more than two dozen countries. To date, these plants have used CarbonCure in more than 20,000 distinct mix designs, treating 350 distinct cements, 200 supplementary cementitious materials and thousands of admixture combinations in concretes ranging from 10 MPa to 100 MPa. By permanently mineralizing CO2 in concrete, CarbonCure’s producer partners reduce cement content in their concrete mixes by an average of about 4-6%, while maintaining equivalent performance and meeting high performance project specifications.

“This is a breakthrough for the industry’s understanding of carbon mineralization,” said Dean Forgeron, Chief Technology Officer at CarbonCure. "This paper shows that CO2 mineralization does more than permanently store CO2 in concrete. It actively influences binder microstructure from the earliest moments of hydration. Industry can now leverage this chemistry to improve cement efficiency and their profitability while delivering the same high-quality products and meeting even the most demanding project specifications.”

====================

Here’s the Google AI response to my inquiry: MIT’s Concrete Sustainability Hub used Raman spectroscopy to reveal how CO₂ injection — in collaboration with CarbonCure — triggers a silica gel intermediate that reshapes the cement matrix into a stronger calcium silicate hydrate network. Do California laws and/or codes require CO injection especially with regards to earthquake events?

No, California laws and building codes do not require CO₂ injection for concrete manufacturing, nor do they mandate it specifically for earthquake or seismic resilience. [1]

While the breakthroughs from MIT’s Concrete Sustainability Hub show that CO₂ mineralization structurally alters the concrete matrix to increase early compressive strength, California’s legal approach remains technology-neutral. [1, 2]

California’s framework handles carbon reduction and seismic regulations through distinct mechanisms:

1. Performance-Based Carbon Mandates (Not Technology Mandates)

California regulates the outcomes of carbon emissions, allowing engineers and concrete producers to decide how to meet those targets. CO₂ injection technologies, like CarbonCure, are highly popular, approved methods to meet these laws, but they are not strictly required. [1, 2]

  • CALGreen Code: Large commercial buildings and schools must comply with mandatory embodied carbon provisions. Builders can use prescriptive paths that limit concrete’s carbon footprint, but they can achieve this via CO₂ injection, structural reuse, or using supplementary cementitious materials (like fly ash or slag). [1, 2, 3, 4]
  • Assembly Bill 2446: This law requires California to achieve a 40% reduction in the carbon intensity of building materials by 2035. It incentivizes technologies like CarbonCure but does not dictate their use. [1]
  • Senate Bill 596: Mandates that the California cement industry reach net-zero emissions by 2045, driving structural market demand for mineralization technologies. [1]
  • Local Codes: Regions like Marin County have implemented maximum cement limits based on carbon emissions, permitting CO₂ injection as a compliance pathway. [1, 2]

2. California Seismic Codes and Concrete

The California Building Code (CBC) governs earthquake resilience through strict, performance-based engineering standards. [1]

  • The Focus: Seismic codes dictate structural ductility (flexibility), shear strength, reinforcement placing (rebar configurations), and minimum structural concrete compressive strength (\(f_{c}^{\prime }\)).
  • The Intersection: Because CO₂ injection improves 24-hour compressive strength by roughly 13%, it helps structural engineers meet the CBC’s rigorous strength requirements faster. However, the code remains completely indifferent to how that strength is achieved, provided the material passes standard ASTM strength and durability tests.

Regards,

Ray

1 Like