Rouzbeh Savary got hooked on concrete when he was young in Tehran, when he often accompanied his developer father Davood to job sites. Even as a 9-year-old, he was mesmerized by the crews making concrete for his father’s multi-story buildings.
“I was very curious about how concrete behaves” and “how it changes from a liquid to a semi-solid and then to a solid,” says Savary, founder and president of C-Crete Technologies, San Leandro, California. “My father also introduced me to ceramics and plaster of Paris”, other moldable materials that harden.
Little did Savary know that his father, who died in late December, was laying the groundwork for his own life’s work. Savary’s fascination with concrete turned into a tireless quest to develop a way to reduce the ubiquitous building material’s considerable greenhouse gas emissions.
He has finally succeeded, after 13 years of trying. Using materials science, engineering, nanotechnology and manufacturing, C-Crete has developed two binders for Portland cement-free concrete. One replaces cement with slag and the other with zeolite, a globally abundant mineral.
The secret of the sauce is that the binders are produced without heat. As a result, they save about a tonne of CO₂ emissions for every tonne of portland cement they replace, says Savary.
Despite his considerable progress, it is still an uphill battle for Savary. “The Portland cement we’re reinventing is low-cost, ubiquitous and has been around for almost 200 years,” he says. “I’m fighting the construction industry’s misperception that Portland cement is the only reliable bond material for concrete.”
Savary is getting help to disprove that perception. In its November debut for a 20-ton level exterior slab, zeolite concrete “showed promise,” says structural engineer Don Davies, principal of sustainable construction consultant Davies-Crooks, which showcased the zeolite at Hubbard’s Corner, a living laboratory for new low-carbon materials.
Earlier last year, Hubbard’s Corner also debuted the C-Crete concrete slag mix, when crews dumped 100 tons on part of the structure. The zeolite mix behaved similarly to the slag mix, says Davies, also one of ENR’s top 25 news producers (see page 48).
Developing the binders required “a lot of chemistry,” says Savary. He first had to figure out how to reverse-engineer Portland cement, which he did while getting his doctorate at the Massachusetts Institute of Technology (MIT). Then, using different rocks, ashes and slag, his team tested about 2,000 recipes. “From each failure, we learned lessons and reduced the starting materials,” says Savary.
In 2010, Savary and another student won first prize in MIT’s annual student-run $100,000 Business Plan Competition. As a result, C-Crete Technologies was born. Since then, most of the nearly $15 million for R&D has come from government grants, including those from the Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E).
“What makes Rouzbeh’s work special is that he’s not trying to reinvent the entire cement industry,” says Madhav Acharya, business partner at Breakthrough Energy. “He understands that he has to work within the existing industry to provide a direct replacement that can be cost-competitive with the legacy bookbinder and available at scale,” adds Acharya, who met Savary while working at ARPA-E.
The C-Crete pilot plant is producing 20 to 30 tonnes per day of binder mainly from slag. The orders include small-scale uses such as an institute, a museum and houses.
Savary’s next step is to increase production. It says it is in talks with an industrial partner for a binder plant that would produce 1 million tonnes a year, the output of a typical cement plant, but has not finalized a business plan.
