The 'salt-like particles' you are seeing I believe is called 'efflorescence'. This is caused by excess moisture moving through your concrete basement walls. Although the interior was probably painted with a "waterproofing" paint, there was still excessive moisture being kept in the walls behind the paint.

Most articles I've read say to try and eliminate the source of the extra moisture. The articles often suggest to look for gutter downspouts and landscaping that do not divert water far enough away from the foundation. You'll need to check this anyway whether it is a fix you can do yourself or need to go to a professional.

The crumbling you see might simply be built up layers of 'salt' that have separated the layer of paint from the actual concrete, which is better than the actual concrete breaking up. You may only need to brush off the loose paint with a wire brush, and wash down the walls with a liquid that will remove the excess salt deposits. Then, when the walls are clear of the salt and loose paint, simply repaint with a waterproofing paint such as DRYLOC.

As long as you have removed the SOURCE of the extra moisture, all should be well. Check out a few books in your local bookstore. They can be more explicit in the techniques.

Good Luck

Thanks Wally, but it appears that my problem is more than just the paint.

There is actually some of the concrete too that has deteriorated. I am taking care of the downspouts--extending them farther away from the house.

Besides brushing away the crumbling concrete and repairing with Drylock--is there anything else to do? Install a dehumidifier, etc? Thanks for the help.

Assuming that your basement is normally dry, if you're only removing a thin layer of concrete in small portions of your basement by brushing out the loose areas and you've eliminated the source of the excess moisture and then recoating with waterproofing paint, that could be the end of it.

How "bad" is the deterioration? If you think you'll be removing LARGE portions of your foundation by brushing away the loose concrete, you may want to have a professional look at it since the foundation is supporting your house. It's generally not a good idea to have "holes" in your foundation for obvious reasons. DryLoc is a brand of "waterproofing" paint that will help create a barrier against water permeating into your basement. It does not "strengthen" a foundation.

Installing a dehumidifier would help reduce interior moisture which will help prevent mold from growing (the source of musty odors), but then the question arises... Where is this excess moisture coming from if I've eliminated one source by waterproofing the walls?

I'd try the repair first and see if that does the trick. If the salt stops appearing especially a few days after a heavy rain, then all is well. If not...then you may need to consult a professional about drainage.

My home 60+ yrs old and built on a concrete foundation. The house is on a creek and with the rapid construction in the surrounding areas, I have experienced basement flooding in 2008, 2011 and 2013. The creek and my residential block become one. With the flooding, the basement walls are now crumbling. I am past the paint level. Cracks are developing and it seems like any area that was sealed, it is just porous gross concrete that seems will never dry. Where do I start and not get scammed by a commercial billboard service?

The info given is very informative, however the use of " " repeatedly as emphasis make the writer look less informed.

I have a different problem. I added on to the back of my house and the wall in my basement that used to be the the back of the house (and is now one of four walls in the new basement) is crumbling. In particular, the lower half...the part that used to be underground. I don't know what to do to stop the crumbling. I can't brush anything on to it...it's like trying to paint a sandcastle. The brush winds up covered in junk and the wall just crumbles.

Cement is crumbling (small pieces of dust/cement) along the exterior of my cement slab where it meets my paver patio. What can be the cause?