Re: Concrete patio resurfacing?
Maybe I'm missing something here but, from your description, you have a concrete slab patio, 3"-4" thick, elevated above the ground with a crawl space underneath. And the depth of some unknown area is 1" to 1 3/4" thick.
What is holding up this heavy slab to make a crawl space?
If itís just a slab (on the ground) covered with a stone veneer, almost any old style, lime based, thin-mortared surface will deteriorate if covered with indoor/outdoor carpet (which holds water to the surface and, essentially, dissolves the mortar over time).
Iím guessing that you have a slab on grade with a stone veneer over it. If the slab is deteriorating then the only reliable choice is to remove it and replace it. Anything else will crack over a very short period of time and fall apart.
If I only knew what I was doing!