I live in a 1989 walkout ranch (driveway and garage on the upper level) built on clay soil. Soil around here is notorious for shrinking over the years. My driveway has been settling and there is now a 2-3" step up into the garage where the two slabs meet. Neither one is cracked (much) and the garage and house seem OK more or less. I'm thinking of getting some estimates for mud jacking the driveway so it's level with the garage slab again. I see there are these polymer foam products they say are lighter and faster and cheaper. I just wonder about the longevity of foam under there. I would not be surprised to find after another 10 years that the foam degraded and the slab sank again. Then you get some concrete guys and they say they can't inject concrete with that foam in there so then you're looking at tearing out the driveway. I just don't trust its durability. BTW the driveway has rebar going into the garage slab, and the sinking has caused pieces to spall off of the vertical face of the garage slab that you can see looking down into the crack. Should we cut that rebar before jacking? I don't want to bust the garage slab because it's in very good shape. Any opinions or experience on the foam, or other advice on mudjacking?