CLIMATEWIRE | The modern world is built on concrete. It holds together driveways, bridges and the buildings in which more than 70 percent of the world’s population makes their home.
But the material is also a climate killer. Its production is responsible for 8 percent of global carbon dioxide emissions — more than the entirety of India’s CO2 emissions.
Remedies have been few and far between, but a California company named C-Crete Technologies says it has developed America’s first carbon-neutral and commercially available ready-mix concrete.
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Its trick is twofold.
The first has to do with ingredients. The production of traditional Portland cement — concrete's main ingredient — requires manufacturers to break down limestone into usable calcium oxide. That typically emits carbon dioxide.
What C-Crete Technologies does instead is to use naturally occurring, abundant rocks — such as zeolite — whose processing does not produce carbon dioxide.
The second step has to do with heat: C-Crete Technologies can manufacture its cement substitute at room temperature. That makes a huge difference, given that cement is typically produced in kilns that reach a scorching 2,600 degrees Fahrenheit, which requires a massive amount of energy.
Rather than kilns, C-Crete Technologies uses industrial milling to pulverize rock ingredients into fine dust for final mixing.
From then on, it’s just normal concrete chemistry. As it cures, calcium oxide from the concrete catches carbon dioxide from the air and merges with it to become calcite. This process, known as carbonation, is effectively a type of carbon capture.
“We are trying to change the picture,” C-Crete president Rouzbeh Savary said in an interview. “This new product exists, and it has — on a 1-to-1 basis with Portland cement — a 100 percent lower carbon footprint.”
Savary founded the San Leandro, California, company in 2010 off a $100,000 grant from the Massachusetts Institute of Technology, Savary’s alma mater.
After more than a decade of research and development, with eight patents to boot, C-Crete’s product has won millions of dollars in government grants plus several early customers.
C-Crete Technologies was given $150,000 as a grant from the California Energy Commission in 2023, and it has received more than $6 million from the U.S. Department of Energy since 2021.
And the company has poured hundreds of tons of carbon-absorbing concrete for sidewalks, foundations and shear walls in Washington state, Arizona, California, and Ontario, Canada.
Savary has set his sights on expanding even more, and he argued that widespread use of his concrete should be a “no-brainer” because it offers the same strength as traditional concrete at a similar cost and without climate pollution.
“It should be a no-brainer,” Savary said of his product, and how it can help with climate change. “The challenge is not scalability. The challenge is not science or technology. The challenge is the mentality of the people.”
Macerich, a real estate investment trust company, has already given C-Crete cement a try.
“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],’” John Haarala, assistant vice president of construction at Macerich, told E&E News over the phone.
Cost, however, might give other potential customers pause. Haarala said the material price of C-Crete concrete was less than 10 percent more expensive than Portland cement-based concrete.
Then, too, there is the issue of transportation.
C-Crete Technologies has one factory to make the stuff, so it's expensive to deliver the concrete to projects outside northern California. Hauling the product to the Phoenix area meant the overall cost of Macerich’s sidewalk “was astronomical,” according to Haarala.
“But it was only because it was a small pour,” Haarala added, saying that bigger projects would mitigate the dollar uptick.
Savary says C-Crete has since decided to absorb the transportation cost for projects rather than passing it on to their customers until it can create more manufacturing facilities across the country and smooth logistics. At present, he added, customers pay “around the same price as Portland cement” when they purchase C-Crete's alternative.
Performance-wise, C-Crete says it stacks up. Concrete is specifically used in high-compression situations, and third-party test results presented to E&E News by C-Crete peg the compressive strength of C-Crete concrete at 8,000 pounds per square inch 28 days after casting. Conventional concrete averages 4,000 to 5,500 psi after 28 days.
Even so, persuading more customers in the construction industry to try C-Crete concrete could be a challenge, said Jeffrey Bullard, a professor of civil engineering and materials science at Texas A&M University.
“The construction industry is extraordinarily conservative” and skeptical of new approaches, he said. And with some reason. Building collapses can kill and leave builders with lawsuits or criminal charges.
Even Haarala — who described Savary as “100 percent top-notch” — said he wouldn’t use C-Crete for anything structural just yet.
“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.”
Though C-Crete Technologies is unique in bringing carbon capture to ready-mix concrete, other startups are trying to soften the carbon footprint of concrete bricks.
Montreal’s CarbiCrete injects atmospheric CO2 into prefabricated concrete blocks as carbon capture. New Zealand-based Neocrete is substituting some cement with volcanic ash, a low-carbon ingredient likely responsible for the longevity of classical Roman concrete.
Bullard said these innovators combined offer a path forward for a difficult climate problem that’s only going to get more pressing. The number of buildings in the world is expected to roughly double over the next 30 years.
Every ton of cement emits about one ton of carbon dioxide, Bullard said. And “when you're dealing with something like 4 or 5 billion metric tons of cement produced worldwide every year, that's a lot of CO2.”
“Their hearts are in the right place. Their economic eye is in the right place,” he said of companies such as C-Crete. “But a lot of times the construction industry — for good or bad — is very resistant to this kind of stuff.”
Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2024. E&E News provides essential news for energy and environment professionals.