I have a 20ft x 30ft (East-West x North-South) concrete slab (in two sections: 20x10 piece on the west, and 20x20 piece on the east) that I'd like to enlarge to about 30ft x 50ft in each dimension. Location is NE Arkansas. I want to build a post-beam wooden carport over it (work area, 2 cars, and a mower) possibly eventually walling it in to be a shop building.
It is on a bit of a slope: N side of slab is flush with ground, S side is about 1 ft above the ground with one corner having a bit of an erosion problem (SE corner), slab corner is exposed about 6 inches above the soil and the hole above the ground goes back about a foot or so under the slab.
I was thinking I could reinforce the exposed corner by digging out some around it and pouring a concrete footer underneath it and hard packing some dirt in as best I can. Then building up some earth from that corner going 20ft east to extend the slab to 50 ft. And then extend the north side 10 ft.
I read that I can drill holes and insert rebar horizontally to tie the slabs together, but I'd also like to pour a fresh slab, say 3 inches thick, above the old one. Should I place some rebar and/or concrete wire attaching it securely to the existing slab via drilled holes with rebar inserted vertically?
Trying to avoid the work/expense of destroying the old slab. It's about 25 years old and doesn't have any cracks, just a really rough surface.
Question: Best advice on pouring a new slab over the existing one and also enlarging it?