I have a problem with the concrete flaking off on a basement wall. Of course it occurs at the bottom of the stairs where everyone ca see it,  The rest of the basement is perfect.  The house is 1940’s vintage with poured concrete walls about 12″ thick.  The concrete has softened in a 4′ X 5′ area and to a depth of 1/2″ the surface layer can be removed with a screwdriver, but after that layer the rest appears to be in good shape.  The areas bordering this area are also in good shape.  Can I remove the remaining loose concrete down to a solid base and apply a bonding agent, and use some type of patching mix?. Any suggestions of brands?.

What causes this kind of problem?  There used to be a entrance above this wall 30-40 years ago could salt be the villain?