[carpdad]

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?

 

[Canarywood1]

That's been around for 20 years or more, apparently there's iron sulfide in the coarse aggregate that was used in the concrete, and over time the water and air has caused it to oxidize and the foundations to crumble.

The quarry operator is the one responsible for that, testing should have found the mineral before it was released from the pit.