How to prepare for 1 3/4" to 4" concrete overlay: rebar vs wire mesh vs fiberglass
I have done the exact same thing using concrete with pea gravel as the rock and fiberglass. Rebar is two thick and will cause problems, mesh might work but in the thin area I think it will still cause cracking.the concrete company can add the chopped fiberglass strands and these hold overlays together quite well, even when it cracks the fiberglass is like micro rebar pieces holding everything together. I also use finer rock but not all the way down to mortar but use pea gravel , some also call Turkey grit. This is stronger than mortar and won't crack as bad as a standard concrete batch at the thin area. If memory serves the fiberglass cost about 15$ per yard, the only negative I have found with the fiberglass is it can end up with some of the fibers sticking up a very slight amount and for bare feet (this was around a pool on a different job) I needed to put down an epoxy coating . other than that I love the fiberglass and use it especially on pours with irregular shapes and thin pours.