INNOVATIVE MATERIALS
Auxetic concrete: energy from the waves When waves batter the coast, energy is generated. Researchers Branko Šavija and Yading Xu from TU Delft want to capture that by using a special type of concrete to create an alternative energy source. For several years, Šavija has been working at the Department of Materials Science and Engineering at TU Delft on materials that behave ‘unexpectedly’, like auxetic concrete, a flexible concrete with special propertie. When loaded, it contracts, but if the load disappears, it expands like a sponge. Normal concrete also moves but not as much. This new concrete contains holes, as a result of which it is less strong but more flexible.
One possible application that the re searchers see is using concrete in coastal protection. Breakwaters consist of large pieces of concrete. The vibrations that arise in the concrete when the waves hit it can be converted into electricity. And there are techniques available to convert such a movement into energy. As the
22 | INNOVATIVE MATERIALS 4 2021
Netherlands has 450 km of coastline, the researchers see a lot of potential in this plan. Šavija and his fellow researcher Yading Xu submitted a proposal to the NWO funding instrument Open Mind last year. In November 2020, during the online edition of innovation festival TEKNOWLOGY, they received a grant of
50,000 euros. With that, they have a year to test their plan. According to the jury, it was a ‘completely original idea to explore an interesting new source of energy’. In their lab, Šavija and Xu are currently working on linking piezoelectric polymer films to the concrete. This soft and
