The world’s most common construction material has a secret. Cement, the “glue” that holds concrete together, gradually “breathes in” and stores millions of tons of carbon dioxide (CO₂) from the air over the lifetimes of buildings and infrastructure.  

A new study from the MIT Concrete Sustainability Hub quantifies this process, carbon uptake, at a national scale for the first time. Using a novel approach, the research team found that the cement in U.S. buildings and infrastructure sequesters over 6.5 million metric tons of CO₂ annually. This corresponds to roughly 13 percent of the process emissions — the CO₂ released by the underlying chemical reaction — in U.S. cement manufacturing. In Mexico, the same building stock sequesters about 5 million tons a year.   

Click here to read the piece in MIT News.

Ancient Roman concrete structures, such as the Pantheon, have endured for millennia despite being unreinforced. A new explainer video explores the mechanisms behind their durability, which research suggests could be attributed to a self-healing ability created by “hot mixing.”

Thank you to our Communications Intern, Allie Garbini, for creating this video.

This research brief by Gwyneth Margaux Tangog, Pranav Pradeep Kumar, Randolph Kirchain, and Hessam AzariJafari presents a context-specific approach for modeling the carbon uptake of a concrete recycling operation. The results demonstrate how increasing stockpiling time, decreasing particle size, and spreading the stockpile over a larger area can help to optimize carbon uptake. Therefore, stakeholders could increase the carbon credits they generate by adopting alternative practices. It is recommended that the brief “Towards Accurate End-of-Life Carbon Uptake Modeling” be read first.

Click here to read the brief, “Site-Specific Carbon Uptake Estimation of Crushed Concrete at End-of-Life”.

How did Ancient Romans create concrete that has survived for millennia? Prof. Admir Masic and team uncovered new evidence in the walls of Pompeii that could inform today’s designs. Their new paper in Nature Communications explores a recently discovered construction site and finds the clearest evidence yet that Roman builders were using the “hot mixing” process that creates self-healing concrete.

As Zach Winn writes for MIT News, “Not only did the concrete samples contain the lime clasts described in Masic’s previous paper, but the team also discovered intact quicklime fragments pre-mixed with other ingredients in a dry raw material pile, a critical first step in the preparation of hot-mixed concrete.”

Prof. Masic explains why this matters today: “This is relevant because Roman cement is durable, it heals itself, and it’s a dynamic system. The way these pores in volcanic ingredients can be filled through recrystallization is a dream process we want to translate into our modern materials. We want materials that regenerate themselves.”

Click here to read the article.

Did you know that concrete “inhales” CO₂ from the atmosphere? Our new explainer video breaks down carbon uptake, the natural process by which cement-based products absorb and permanently store CO₂ over time. The amount of CO₂ sequestered depends on factors like product type, surface-area-to-volume ratio, and exposure to the elements. With thoughtful design strategies, this process can be amplified to further reduce net emissions.

Understanding and accounting for carbon uptake is critical when assessing the environmental benefits and impacts of cement-based products. We are grateful to Alessandra Garbini and Esther Song for their leadership in developing this video.

Try our Whole Life Cycle Carbon Uptake Tool.

Read the interim report, “Accounting for Carbon Uptake in the EPDs of Cement-based Products.”

This research brief led by Drs. Pranav Pradeep Kumar and Hessam AzariJafari examines how the quantity of atmospheric carbon dioxide sequestered by crushed concrete is affected by the size distribution of aggregate particles (grading) and their paste content. The brief finds that fine particles of crushed concrete exhibit an approximately 270% higher paste content and 36% higher degree of carbonation than coarser particles. The CSHub model finds 33% higher uptake than existing models applied to the same representative sample, underscoring the importance of incorporating grading variability into end-of-life (EOL) carbon uptake assessments while more accurately capturing paste content variability.

Click here to read the brief.

The April 22nd Resilience Executive Roundtable@MIT brought together leaders across construction, insurance, fire safety, and other industries to discuss the need for stronger construction to protect homes, lives, and communities from intensifying natural hazards.

The MIT CSHub has created a summary report which provides an overview of the roundtable, barriers and opportunities for achieving more resilient construction, as well as action items and next steps.

Click here to read the summary report.

Thank you to our steering committee: the National Association of State Fire Marshals, National Ready Mixed Concrete Association, U.S. Resiliency Council, MIT Humanitarian Supply Chain Lab, National Institute of Building Sciences, American Cement Association, Build With Strength, Smart Home America, Building Resilience Coalition, Concrete Advancement Foundation, and MIT Center for Real Estate.

Our research brief led by alumna Dr. Ipek Bensu Manav examines the emissions impact of materials choices and repairs in hazard-prone areas. The Florida case study demonstrates that durable, hazard-resilient materials may contribute to lower life cycle emissions despite higher upfront emissions, thanks to savings in the repair and replacement stages.

Click here to read the brief.

This research brief led by Dr. Haoran Li evaluates the potential benefits and costs of increasing ready mixed concrete (RMC) truck gross vehicle weight limits beyond current federal thresholds, while remaining within the trucks’ capacity. In many cases, current weight limits prevent trucks from operating at capacity. In a modeled case study of a Pennsylvania interstate, the team found that allowing heavier gross loads reduces the number of RMC trucks needed to deliver the same volume of concrete, lowering costs, GHG emissions, and fuel use without affecting pavement deterioration or the fuel use or performance of other vehicles.

Click here to read the brief.

AI is reshaping the future of concrete. In MIT News, a CSHub and Olivetti Group team explains how they’re using chatbots and machine learning to find new materials that can replace a portion of cement in concrete. As industry looks to reduce costs and emissions, demand for traditional cement supplements is outstripping supply. The MIT team’s method scans through hundreds of thousands of pages of scientific literature and over a million rock samples to find alternative, globally available candidates from demolished construction materials to biomass.

Click here to read the story in MIT News.