Spalling and Efflorescence on Basement Wall
I have been having a problem for many years now with an ever-so-slightly (I can't even tell by touching it) damp concrete basement wall over which plaster was applied 65 years ago when the house was built. The rest of the basement is utterly dry (and finished and liveable) and the carpeting right up against the problem wall is dry to the touch as well (so the dampness is not that bad). However, it is producing patches of efflorescence in an area about 5 feet high by 3 feet wide. I have scraped off the affected plaster right down to the concrete. Near the bottom of the wall I have discovered for the first time that even the concrete seems somewhat "soft". When hit with a chisel it actually sounds hollow and I can dig bits of it out if I want to (but I don't want to!).
My guess is that the advice here will be to have the walkway on the outside of the wall regraded. We won't be able to do this until at least next Spring. Has permanent damage been done to the concrete wall and in the meantime, can anyone advise me on how to repair the inside wall so that it doesn't look so hideous all winter (it is in a high traffic area at the bottom of our basement stairs and we use the basement quite a bit. Can I apply some sort of sealer to the bare concrete and fill in the patches where the plaster has fallen off with some other kind of plaster? I don't mind doing all of this work again once we get the outside regraded because it is such a small area, but what products should I use for this purpose (if that is what you nice folks recommend I do)?
I appreciate any advice you can give me.