Researchers shed new light on ancient concrete’s extraordinary durability

While the pozzolanic reaction is of fundamental importance,” said Monteiro, Professor of the Graduate School in civil and environmental engineering, “our findings suggest that carbonation over a long period of time also enhances the durability of concrete and can help it seal cracks as it ages.”

That was also my first thought when reading the headline, but this paper is specifically discussing that there may be more going on than previously thought.