It is always a bit annoying to read an article based on the work of someone specialized in one area that talks down specialists in another area. Is is definite

It is always a bit annoying to read an article based on the work of someone specialized in one area that talks down specialists in another area. Is is definitely interesting to read about some unexpected properties that ancient concrete with volcanic ash as one of its ingredients has. For modern cement there is a different set of choices for binding materials, were you can choose the ingredients that are locally good available. Also there are definitely mistakes that get made in modern construction. - Maybe the structure has enough rebar to handle the forces that act on the structure, but not enough to prevent the small cracks that hurt durability (although that is something that should be checked). - Maybe the detailing of the rebar is not correct. Lapping lengths are too short. Often I see that the workers who put in the rebar come up with creative solutions but understanding why it now doesn't work well is outside their expertise. - Maybe the concrete layer that protects the rebar (covering) from rusting is to thin or to porous. The amount of covering required depends on the exposure classification. And the concrete mixture influrences how porous the concrete becomes over the years. For modern engineering you specify the exposure classes that a structure falls in. Carbonatation (https://en.wikipedia.org/wiki/Carbonatation https://en.wikipedia.org/wiki/Carbonatation), a reaction where calcium in the concrete with CO2 in the air, which changes the acidity in the concrete. Chlorids, from sources such as seawater or de-icing salts, also impact the acidity of the concrete. Chemical acids, basically everything biological such as milk, beer, manure, and other acids dissolve the calcium. And frost can cause parts of the concrete to flak off. All those effects can get worse if the concrete gets porous. But all are well understood problems that inform the necessary mixture.