Alkaline contamination?

Repairing a foundation is reinforcing its components by resurfacing them. More specifically, it means removing all crumbling particles and applying a new coat of concrete on the damaged walls. This helps to restore the structural homogeneity of the foundation and soundness of the building. This is the least expensive solution, which is very effective in the mid and long term. In some cases, only part of the foundation may be weakened. It is then necessary to replace the damaged section with form work connected to the rest of the foundation. This type of repair is often seen in areas where the property is on a negative slope or on a corner that is prone to frost.

Moisture/water on the outside of the foundation is permeating the walls caucing the "efflorescence". You may need to solve that issue. Yoiu can try scraping and patching with cement. The use Drylock waterproofing paint.

I would recommend a professional for this job. There is no telling how deep your crumbling goes in. Please consider this a top budget priority and safety for the engineering strength of your home.

Omg, get a foundation specialist in asap.

I used to build concrete basements years ago. I hope there is some new tech for you. The way we "used" to fix this when I was doing it, The house would be "lifted" off the foundation wall. Supported by long beams that stretched out past our work area we needed. We would tear out all concrete and surrounding soil to about three feet out and to below the floor grade by about two feet. If the floor was "bad" it would go as well. Then we would rebuild everything. from the bottom up. Set the house back down on the new foundation, refinish the concrete exterior with the best waterproofing system available (they are even better now) add a complete below grade drainage and gutter drain system, then backfill. Yes, it was expensive!