Concrete stores CO2 and becomes more durable and stronger in the process

There have already been a whole series of attempts to enrich concrete with CO2. The calcium contained in large quantities absorbs it well, so there are several opportunities to add it during production.

This step would certainly be necessary. The respiratory toxin, whose concentration in the atmosphere has already increased by around 50 percent due to human activity, is emitted in huge quantities during concrete production. The entire industry is responsible for 8 percent of global CO2 production.

However, the results of previous experiments were either far too costly or led to lower material quality. And that's really not what you want for the basic material of bridges and houses.

With a new approach, Northwestern University, Illinois, USA, and the cement manufacturer Cemex have tackled the problem. Even before the actual production process, water is only minimally enriched with cement. This suspension is then carbonized. The CO2 is pressed into it like mineral water gets carbonated.

The further steps in concrete production remain the same, except that some of the CO2 emitted during production is now back in the responsible product. Even better: tests with the newly produced building material show slightly improved strength and durability compared to conventional concrete.

Two birds with one stone. However, the proportion remains negligible. If global production were to be adapted in this way, it would be equivalent to saving the exhaust emissions of around 18 million cars. The problem is that the equivalent of the exhaust gases from more than 500 million cars are emitted every year. That's a lot, and the new method can currently only compensate for 4 percent of it.

But there are rays of hope: the concrete loses more than half of the originally stored CO2 during hardening. Progress could still be made here in the future. And the duration of storage itself also plays a role, as concrete buildings have a considerable lifespan. If the captured CO2 is fixed for decades or longer (keyword: Pantheon), this would also be a contribution.