My home is 30 years old is has a concrete driveway and garage. Just recently I noticed small pieces of concrete all over the ground and, when I examined the garage, I saw numerous holes in garage flooe where the concrete had chipped out. Each hole (pit) ishas a dark circle around it. Whatr could be the cause (my garage is starting to look like is has the chicken Pox) and how can it be fixed?

What is the climate where you live?

You're describing something called spalling. Google it for more information.

30 years is pretty good, so it does not appear to be caused by improper mix or curing. If you have winter where you are, road salt is common cause. You can seal the concrete to try and stop the damage.