The walls have been painted and the wall is crumbing in several places behind the paint and salt like particles have formed.
Moist basement concrete wall repair crumbling.
First off brush off any loose material from the basement walls.
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Wash the walls with an acidic solution check on amazon to neutralize the salt completely and allow to dry for a few hours.
Apply small amounts of water over a short period until it has absorbed water deep into the wall.
Now you should apply water to the wall where you will be applying the mortar.
The wall needs to be moist so that the old concrete won t leach moisture out of the mortar that you apply and cause the repair to fail.