The concrete deck on my build-in-1937 house seems to be falling apart from the bottom. The deck itself is a 4.5 inch slab connected to the front of a brick house, and by two brick pillars in the corners. Someone added another cinderblock pillar in the middle of the falling apart area (pictured), and tried to patch the damage, but most of the patch has fallen away. (There's wiring indicating an AC compressor used to reside under the deck.) The falling apart area is deep enough in parts to expose whatever 1930s rebar looks like, which is flaking away. Pictured is the worst part, where it's more than an inch deep.
This looks like more than a simple patch I could cover with epoxy. Does anyone have any advice on how I should proceed? Can I recover this with new cement? I'm worried (without any actual evidence) that the edge of the deck may not be as stable as it looks from the top!