Associate Professor of Earth and Planetary Sciences Tiziana Vanorio has revolutionized traditional cement production by drawing inspiration from the volcanic chemistry of Pozzuoli, inventing a cement with a significantly reduced carbon footprint.

In 79 AD, Roman writer Pliny the Elder marveled at how Pozzuoli volcanic ash (now known as pozzolan) hardened into stone when mixed with water—a property that enabled the construction of remarkably durable structures such as the Pantheon. Today, the pillars of modern skyscrapers and homes rely on cement, but cement production requires heating limestone to over 1400°C (calcination), a process responsible for about 8% of global CO₂ emissions—one of the largest industrial sources of global warming.

To address this, Vanorio drew inspiration from her hometown near the Phlegraean Fields volcanic region in Pozzuoli. Together with Stanford colleagues—including materials science professor Alberto Salleo and chemical engineering associate professor Matteo Cargnello—she explored a mixing design using rocks that are more abundant than typical volcanic ash and have already been naturally heated. The new method uses rocks that do not contain carbonates, which release CO₂ when heated.

Vanorio explained that she was inspired by nature’s ability to bind rocks, and with her colleagues, she applied scientific and engineering techniques to advance the concept further. By transforming a ground mixture of naturally “pre-cooked” igneous rock into a synthetic pozzolan-like binder, her laboratory discovered a way to intentionally grow a network of microscopic fibers within the material—mimicking the natural cementation of rock sediments—rather than relying on steel reinforcement as in conventional concrete.

Vanorio and her colleagues have now founded a company called Phlego, which has received a technology license from Stanford University to bring this greener cement to market. Given that Vanorio was born in Pozzuoli, Phlego can be seen as a crystallization of “pozzolan.”