The concrete basement of our 80-year-old six-unit apartment building is
generally in pretty good shape, except in one of the corridors the concrete
has buckled up badly.
It's almost as if there were some roots growing underneath, but that cannot
possibly be the case.
There seems to be an air-pocket beneath the buckle.
I can break up the top layer easily, but my question is, just what type of
concrete do I use to replace it? It's smooth-finish, of course -- not like a