[Image above] Yang En-Hua, lead researcher and assistant professor at NTU’s School of Civil and Environmental Engineering, holds a small slab of ConFlexPave, the bendable concrete he and his team invented. Credit: NTU Singapore

Concrete is one of the most widely used construction materials in the world. And although it’s pervasive, it’s definitely not clean to produce. In fact, today’s standard Portland cement, which is extremely carbon-intensive to make, accounts for nearly 5% of the world’s total carbon emissions.

But modern civilization as we know it would cease to exist without concrete—so engineers are working toward innovative, “greener,” energy-efficient concrete manufacturing solutions.

Some scientists are returning to simpler times and investigating the ancient Roman secret to more ductile concrete. Geophysicists at the Stanford University School of Earth, Energy and Environmental Sciences (Stanford, Calif.) who discovered concrete-like rock deep within a dormant Italian volcano say this discovery could explain how ancient Romans invented the compound used to build structures like the still-standing Pantheon and Colosseum.

Meanwhile, materials scientists at Northwestern University’s Center for Sustainable Engineering of Geological and Infrastructure Materials in Evanston, Ill., are looking toward the future. They developed a method for making Martian concrete using materials that are available in generous supply on Mars and without using water—a resource that will be limited and precious on the planet.

And closer to home, researchers at Rice University in Houston, Texas, are leveraging concrete’s brittleness, saying the key to greener concrete manufacturing practices lies in the material’s defects.

Most recently, scientists from Nanyang Technological University’s Industrial Infrastructure Innovation Center in Singapore are taking a new approach to uncovering the formula for better concrete. They’ve invented a new type of concrete called ConFlexPave that is bendable yet stronger and longer lasting than standard concrete.

“This innovation allows the creation of slim precast pavement slabs for quick installation, thus halving the time needed for road works and new pavements. It’s also more sustainable, requiring less maintenance,” explains an NTU press release.

Here’s how bendable concrete breaks the mold:

Traditional concrete is made of cement, water, gravel, and sand—all ingredients that contribute to the material’s hardness, but do nothing to give concrete structures flexibility… and why you might have stubbed your toe on that deep, uprooted crack in the sidewalk outside your house this summer (more than once).

ConFlexPave, on the other hand, “is specifically engineered to have certain types of hard materials mixed with polymer microfibers,” the release explains. These synthetic fibers allow the concrete to flex and bend under tension.


Conventional concrete (left) vs bendable concrete (right) after a bend test. Credit: NTU Singapore

To make ConFlexPave a reality, the researchers had to take a microscopic look at how components of the materials interact with one another, according to Yang En-Hua, lead researcher and assistant professor at NTU’s School of Civil and Environmental Engineering.

“With detailed understanding, we can then deliberately select ingredients and engineer the tailoring of components, so our final material can fulfill specific requirements needed for road and pavement applications,” Yang explains in the release. “The hard materials give a non-slip surface texture while the microfibers, which are thinner than the width of a human hair, distribute the load across the whole slab, resulting in a concrete that is tough as metal and at least twice as strong as conventional concrete under bending.”

Currently, tablet-sized slabs of ConFlexPave has been successfully tested at NTU laboratories, but the team plans to scale up manufacturing of the novel material to put it to the test in larger volumes throughout the next three years.