A group of researchers from Switzerland, the US, Canada and Norway have said the most common cause of degradation and failures of reinforced concrete structures is chloride-induced corrosion of embedded steel elements.

They warned that the issue is a “pervasive, urgent problem” that requires more attention and public awareness.

An underlying concept of a chloride threshold is widely used, and all existing models to forecast corrosion performance of reinforced concrete structures exposed to chloride environments are based on this one common theoretical concept.

But the researchers believe change is needed to address the growing challenges of ageing structures losing functionality and potentially collapsing, as well as their associated greenhouse gas emissions.

“Corrosion of steel within concrete is a complex phenomenon,” said Ueli Angst, from ETH Zürich in Switzerland.

“In the generally very high alkaline environment of concrete, where the pH may be higher...