It sounds a bit strange, but some materials become stronger when subjected to stress. Why is that, and why do they eventually fail anyway?

What doesn’t kill us makes us stronger, said philosopher Friedrich Nietzsche. Who would have thought that a similar notion might apply to materials?

To explain, we have to start with something almost as strange.

The builders of the Kristiansten fortress in Trondheim in the 17th century put the remains of dead animals into the construction material. As the animals rotted and emitted gases, they made the material porous and thus stronger.

Photo: Shutterstock, NTB Scanpix
“The reason concrete is so strong is because it’s so weak,” says Professor Alex Hansen, and already here our head may start to spin a little.