It's in the news that many house foundations are cracking apart because the aggregate used in the concrete. The stones are called pyrrhotites and these homes are in Connecticut. It's NY times article.
I believed concrete is concrete, but this is a nightmare for many people there. Does this mean taking a core sample when buying a house? Sounds ridiculous and nobody on the selling side would want it, but if I can't believe in concrete, what can I believe?