Thanks for the info. I thought there might be some kind of material or something like an epoxy that's flexible in hot n cold weather. Their house has slowly sinking in the past 20 years. I'm guessing thats the reason for the cracking.
There is a section on the garage floor that has been cracking for well over 15 years. It has slowly spread over the years. Looking to help out a family member fix this but don't know the correct way to repair it. As seen in the pic there is plastic under the layer of concrete. Any help on...