Building materials to protect the climate

The production of concrete contributes around nine percent of global CO₂ emissions. If we want to combat climate change, we therefore need new types of concrete that last longer, produce fewer greenhouse gases and are so stable that it is possible to build slimmer – i.e. more material-efficient – structures. Empa researchers came up with an idea: Could a self-prestressing concrete be the solution?

Researchers are already experimenting with reinforced concrete elements that are prestressed by heat rather than hydraulically. Moslem Shahverdi from Empa's Structural Engineering lab would like to go one step further: Small pieces of wire, just two to three centimeters long, are distributed in the concrete. If these wires, which are made of a special alloy known as shape memory alloys (SMA), are heated, they contract. This could produce concrete that prestresses itself in all spatial directions at the push of a button, as it were. And the material would be much stronger and more durable than conventional reinforced concrete we have been using for 140 years.

Researchers from two other Empa labs are supporting Shahverdi: Experts from the Concrete and Asphalt lab are developing concrete mixtures with a lower carbon footprint. And colleagues from the Mechanical Systems Engineering lab, who specialize in calculating the strength of small and large building components, can suggest particularly promising experimental setups to Shahverdi using so-called finite element simulations. This significantly reduces the number of actual experiments and helps researchers reach their goals faster.