I would like to replace a small section (approx. 2'x3') of the basement slab. The crumbling section is near the foundation wall, which also has some damage from spalling. I have regraded the exterior away from the house and extended the gutter downspouts, so I think the underlying moisture problem is more or less solved.
The slab appears to be original, nearly 100 years old, and is about 1 1/2" thick. I am assuming it doesn’t have much structural value given how thin it is. I am planning on demolishing the concrete in a slightly larger area, add gravel as needed, compact it and then fill it with fresh concrete.
Is it a problem that the section is close/above (I assume) the footer of the foundation wall? Can I use regular mix, or do I need something like polymer modified concrete to help with bonding to the existing slab? I would hire a professional, but they're not interested in small jobs in my area.