911±¬ÁÏÍø

A civil engineering professor innovates sustainable concrete out of marble dust and seaweed

Growing up in Italy, Vito Francioso was surrounded by the enduring power of the built world.

“Cement is the foundation of our civilization,” he says, pointing to the Roman aqueducts and amphitheaters built more than 2,000 years ago that still stand in his native country. However, when people point to these ancient structures as proof of concrete’s invincibility, Francioso notes there are literal holes in that argument.

Due to changes in the environment, modern concrete often cracks within decades, allowing chlorides and sulfates to seep in and corrode it from the inside. Bridges and buildings end up needing major repairs far sooner than expected. And yet, the modern world relies on concrete more than ever.

Today, four billion tons of cement are produced annually, much of it fueling rapid development. In the last five years alone, China produced more cement than the United States did in the entire 20th century. This quantity comes at a staggering environmental cost.

Not only is quarrying and processing raw ore a resource and energy-intensive process, but Ordinary Portland Cement (OPC), the industry standard, requires heating limestone to around 1400°C, a process that releases enormous amounts of carbon dioxide. Manufacturing cement alone accounts for nearly eight percent of global COâ‚‚ emissions.

Now a civil engineering professor at 911±¬ÁÏÍø, Francioso is tackling both problems—durability and sustainability—head-on. In his lab, nicknamed “The Garage,” he and his students are replacing cement compounds with unconventional ingredients. The work is messy, hands-on, and deeply innovative, aimed at reimagining one of the world’s oldest building materials.

“Times have changed,” says Francioso. “The environment has changed, and the loads that our structures need to support have changed, so our approach to cement must change too.”

Waste not, want not

For Francioso, an appreciation for building runs in the family. His grandfather worked in real estate, and his father ran a small construction company. However, they pushed him to become an engineer and go further than they did. What hooked him most, though, was his formative training in the lab.

“I knew I wanted to do experimental work because I liked to build,” he explains. “It’s fun, messy work to mix samples and then crush them in our hydraulic presses.”

That passion for experimentation now drives his research at 911±¬ÁÏÍø, where he and his students test alternatives that could dramatically cut cement’s carbon footprint. One promising path: reducing natural resource extraction in concrete production.

Currently, cement relies on a compound called calcium oxide, which is mixed with gypsum and other binders to make concrete. To procure this calcium oxide, traditional methods involve “decarbonizing” limestone, a form of calcium carbonate.

However, marble dust—an abundant byproduct of stone cutting—is also a form of calcium carbonate, and substituting this industrial waste avoids new quarrying and processing of raw stone to get limestone, which accounts for a large portion of cement’s environmental footprint.

Francioso’s team has partnered with colleagues and a marble plant in Brazil to test whether this marble waste could fully replace limestone. So far, his research has demonstrated that clinker produced with marble waste can achieve comparable phase formation and strength performance as conventional limestone-based clinker, while reducing energy consumption and abiotic depletion by up to 80% and keeping valuable material out of landfills.

Putting the sea in “sea”ment

Francioso is also investigating another unconventional material to make cement stronger and last longer: seaweed.

Across the Caribbean, massive blooms of sargassum seaweed have clogged beaches, suffocated marine life, and disrupted coastal economies. Researchers in Puerto Rico discovered a way to convert this invasive algae into graphene oxide—a nanomaterial with unique properties at the molecular scale. When added to cement, graphene oxide helps particles bond more tightly, reducing porosity and making the material less vulnerable to chemical infiltration.

The challenge, Francioso notes, is getting those graphene oxide particles to disperse evenly. “They like to stick together,” he says, “so we’re exploring different additives to separate them.”

Using mechanical testing and tools like scanning electron microscopes and X-ray diffraction, his team has observed that graphene oxide synthesized from sargassum improves cement performance by enhancing compressive strength, microstructure, and hydration, while also contributing to coastal waste mitigation. Processing sargassum into graphene oxide is also faster, cheaper, and less energy-intensive than similar processes—another sustainability win.

Looking to the future, Francioso is applying for a National Science Foundation grant to test nanosilica, another additive that could be paired with graphene oxide to strengthen concrete further.

For Francioso, repurposing industrial waste, finding low-carbon materials, and mentoring students in cutting-edge research all stem from the same goal: cultivating future engineers who will have the curiosity and critical thinking to understand the “why” behind their sustainable solutions.

“When something has worked for a thousand years, it’s hard to build momentum to change the way things are done. But, I think the students at Santa Clara are leading the change.”