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.
Moist basement concrete wall repair crumbling.
Mist the wall with water and then apply a coat of thoroseal with a latex additive check on amazon.
The walls have been painted and the wall is crumbing in several places behind the paint and salt like particles have formed.
Now you should apply water to the wall where you will be applying the mortar.
The walls in my 63 yr old full walk out basement are crumbling in spots.
Apply small amounts of water over a short period until it has absorbed water deep into the wall.
First off brush off any loose material from the basement walls.