My 100 year old house has a nice thick poured concrete foundation. The surface, though, is heavily spalled. In places, about 1/4 to 1/2 an inch has softened and crumbled off. What’s left is pretty sturdy, but is ugly and dirty. Is there anything a do it yourselfer can do to clean it up, harden the remaining concrete to prevent further damage, and put a smooth finish coat back on?
I’m not an expert on foundation repair but I am a civil engineer. Concrete, if mixed properly, should continue to harden for the rest of its existence, approaching an upper boundry. If the concrete is soft and spalling, it was probably a bad mix made with too much water. Or the rebar could be rusting and pushing off the surface.
I’d get it inspected by a foundation guy. If the remaining concrete is good, there’s not reason it couldn’t be patched. I did find this government page on seafort preservation, oddly enough, that has a littel section on spalling repair. I’m sure there’s more out there too…
There are a variety of self-leveling compounds on the market that could fix your problem. Check with a self-help store.
Both Thoro and Conproco offer many products for repair and rehabilitation of cementitious surfaces. Find a local supplier and spend time to describe your problem. They should be able to point you in the right direction.