Concrete innovation promises leaner structures

Scientists at the Swiss Federal Laboratories for Materials Science and Technology (Empa) have developed self-pre-stressed concrete elements. Their innovation makes it possible to build leaner structures that use less material.

A team of scientists at Empa has developed a new technology that has the potential to produce and use concrete in a more sustainable manner by reducing the amount of materials used when pre-stressing concrete elements.

In conventional pre-stressing technology, steel reinforcements are anchored on both sides of the element before the concrete is cast, put under tension and then released again after the concrete has set. But as steel is susceptible to corrosion, the concrete layer around the pre-stressing steel must have a certain thickness, according to an Empa press release.

Since the 1990s, researchers have looked into replacing steel with carbon fiber-reinforced polymers (CFRP) as these do not corrode. However, the pre-stressing process for CFRP is very expensive and far more complicated that that of steel.

The Empa team has now overcome these problems by completely dispensing with anchoring on both sides of the concrete element thanks to a special formula that allows the concrete to expand as it hardens. As a result, the concrete puts the CFRP bars in its interior under tension and thus automatically pre-stresses itself. Laboratory results show that the self-pre-stressed CFRP concrete elements can bear loads that are comparable to those that were conventionally pre-stressed.

“Our technology opens up completely new possibilities in lightweight construction,” said Mateusz Wyrzykowski, who is leading the Empa team along with Giovanni Terrasi and Pietro Lura. “Not only can we build more stable structures, we also use considerably less material.”

The team, which was recently granted patents in Europe and the U.S. for their self-pre-stressing concrete technology, are now developing new applications in cooperation with industry partner BASF.

Image credit: Empa

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