Obviously, this is a summary of what’s happening, but it doesn’t appear the homeowners have much recourse, The quarry and concrete maker don’t appear to have engaged in fraudulent behavior, or tried to deceive people. WHen a problem like this crops up after 30 years, it seems hard to find fault.
The foundations can be remade even with the house in place. You have to jack it up and do one wall at a time..it’s a process, but I grew up with a stepdad who knew how to do it...and I mixed EVERY load of concrete...by hand, with a hoe that rebuilt the entire foundation of our houses. The names of my siblings and I are written in that concrete with the year...and those houses still stand strong.
Our cellars were old...the kind made with bolders, and we had to dismantle the walls to replace them with the concrete, and then the floors, too.
If the contractors are at fault for bad mixes, it’s time for them to ante up!
Companies are routinely sued for environmental damage decades later. In many of these cases everything was "by the book" at the time it was done.
If any had a crack before sale, fault is easy to assign.
Those who purchased after the problem was well-known also probably have recourse.
Certainly the concrete supplier and potentially those who poured it are not likely to face any jeopardy after 30 years.
But it's likely there were some home sellers and inspectors who are at risk.
And, of course, the banks holding the mortgages. They're screwed.