Concrete is foundational to modern infrastructure, comprising driveways, bridges, and the buildings where over 70 percent of the global population resides. However, its production significantly impacts the climate, accounting for 8 percent of global carbon dioxide emissions—more than the total emissions of India.

Addressing this issue, C-Crete Technologies, a California-based company, claims to have developed America’s first carbon-neutral and commercially available ready-mix concrete. Their innovation involves a dual approach to overcoming the environmental drawbacks of traditional concrete.

The first aspect pertains to the materials used. Conventional Portland cement, the primary component of traditional concrete, is produced by heating limestone to extract calcium oxide, a process that releases carbon dioxide. C-Crete Technologies, in contrast, utilizes naturally occurring and abundant rocks like zeolite, whose processing does not produce carbon dioxide.

The second innovation involves the temperature at which the cement is produced. While traditional cement manufacturing requires kilns that reach temperatures of up to 2,600 degrees Fahrenheit—consuming substantial amounts of energy—C-Crete Technologies manufactures its cement substitute at room temperature. Instead of using high-temperature kilns, the company employs industrial milling to grind rock ingredients into a fine dust for final mixing.

The process continues with standard concrete chemistry. As C-Crete concrete cures, the calcium oxide within it reacts with atmospheric carbon dioxide to form calcite through a process known as carbonation. This reaction acts as a form of carbon capture.

“We are trying to change the picture,” stated C-Crete president Rouzbeh Savary. “This new product exists, and it has — on a 1-to-1 basis with Portland cement — a 100 percent lower carbon footprint.” Savary, who founded the company in 2010 with a $100,000 grant from the Massachusetts Institute of Technology (MIT), has invested over a decade into research and development, resulting in eight patents.

C-Crete Technologies has received substantial financial support, including $150,000 from the California Energy Commission in 2023 and over $6 million from the U.S. Department of Energy since 2021. The company has already used its carbon-absorbing concrete in various projects, including sidewalks, foundations, and shear walls in Washington state, Arizona, California, and Ontario, Canada.

Savary is aiming to expand the use of C-Crete’s concrete further, advocating for its broader adoption due to its strength and climate benefits. “It should be a no-brainer,” Savary said, emphasizing the potential impact on climate change. “The challenge is not scalability. The challenge is not science or technology. The challenge is the mentality of the people.”

Real estate investment trust Macerich has experimented with C-Crete concrete. John Haarala, assistant vice president of construction at Macerich, recounted, “I came across C-Crete, and we just happened to reach out to Rouzbeh (Savary) and said, ‘Hey, can you tell us a little bit about your product? We have a test case. We’d like to use it for some sidewalk at one of our malls in Scottsdale [Arizona].’”

Cost remains a concern for potential customers. Haarala noted that C-Crete concrete was less than 10 percent more expensive than traditional Portland cement-based concrete. Additionally, the transportation of C-Crete’s product from its sole factory in northern California has proven costly, especially for smaller projects. “Hauling the product to the Phoenix area meant the overall cost of Macerich’s sidewalk ‘was astronomical,’” Haarala explained. However, he noted that larger projects could offset the increased cost.

To address transportation challenges, Savary mentioned that C-Crete has begun absorbing transportation costs for projects rather than passing them on to customers. Currently, customers pay “around the same price as Portland cement” for C-Crete’s alternative. Performance-wise, C-Crete’s concrete has shown promising results, with compressive strength reaching 8,000 pounds per square inch 28 days after casting, compared to the 4,000 to 5,500 psi typical of conventional concrete.

Despite these advancements, persuading the construction industry to adopt C-Crete concrete remains a challenge. Jeffrey Bullard, a professor of civil engineering and materials science at Texas A&M University, noted that the industry is “extraordinarily conservative” and wary of new methods. The risks associated with building failures and potential legal repercussions contribute to this skepticism.

Even Haarala, who praised Savary’s expertise, expressed caution regarding the long-term durability of C-Crete concrete. “We don’t know how it’s going to stand up in five years or 10 years,” he said. “We have no reason to indicate or believe it’s going to fail, but we don’t know that yet.”

While C-Crete Technologies is pioneering carbon capture in ready-mix concrete, other startups are exploring alternative approaches to reduce the carbon footprint of concrete. Montreal’s CarbiCrete injects atmospheric CO2 into prefabricated concrete blocks for carbon capture, and Neocrete of New Zealand uses volcanic ash to partially replace cement, leveraging the longevity of classical Roman concrete.

Jeffrey Bullard acknowledged the potential of these innovations, stating, “Their hearts are in the right place. Their economic eye is in the right place.” However, he also highlighted the formidable challenge of convincing an industry resistant to change. With global cement production expected to double over the next 30 years, addressing the carbon footprint of concrete is becoming increasingly urgent. Every ton of cement produced emits roughly one ton of carbon dioxide, underscoring the importance of finding viable solutions.