I have a concrete driveway and path to my front door. Much of it has become unlevel and I'm contemplating having it mud-jacked. However, before I do, I wanted to know how I could easily tell when a piece of concrete was too far gone to mud-jack and just needs replacing.
The key criteria is how stable the ground beneath the concrete is.
If the ground is stable you can patch and mud-jack your driveway efficiently. Otherwise patches of any kind are a waste of time - after you patch the pieces won't be perfectly attached to each other, so they will come apart again in no time. If that's the case you have to remove the concrete, remove a layer of ground beneath it, put a layer of crushed stone, ram the crushed stone thoroughly and then put the new layer of concrete. That will stabilize the ground and you'll have the driveway with decent lifetime.